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  • Triticum aestivum  (266)
  • maize  (201)
  • Springer  (467)
  • Wien : Geolog. Bundesanst.
  • 2005-2009
  • 1990-1994  (467)
  • 1960-1964
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 207-214 
    ISSN: 1573-0867
    Keywords: available P ; citrate insoluble P ; phosphorus sources ; triple superphosphate ; Triticum aestivum ; water soluble P ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse study was conducted to determine if soil pH affects the requirement for water-soluble P and the tolerance of water-insoluble impurities in TSP fertilizers. Two commercial TSP fertilizers were selected to represent a range in phosphate rock sources and impurities. Phosphate fertilizer impurities were isolated as the water-washed fraction by washing whole fertilizers with deionized water. TSP fertilizers with various quantities of water-soluble P (1.2 to 99% water-soluble P) were simulated by mixing the water-washed fertilizer fractions or dicalcium phosphate (DCP) with reagent-grade monocalcium phosphate (MCP). The fertilizers were applied to supply 40 mg AOAC available P kg−1 to a Mountview silt loam (fine-silty, siliceous, thermic Typic Paleudults). Wheat (Triticum aestivum (L.)) was harvested at 49 and 84 days after planting. Soil pH values at the final forage harvest were 5.4±0.16 and 6.4±0.15. At a soil pH of 5.4, the TSP fertilizers required only 37% water-soluble P to reach maximum yields while at pH 6.4 the fertilizers required 63% water-soluble P. Results of this study show that higher levels of water -insoluble P can be tolerated in TSP fertilizers when applied to acid soils. Phosphorus uptake was not affected by soil pH, but for the mixtures containing the fertilizer residues the source having the lowest level of Fe and Al had a higher relative agronomic effectiveness.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 43-57 
    ISSN: 1573-0867
    Keywords: Bicarbonate soil test phosphorus ; relative effectiveness ; rock phosphate ; superphosphate ; Triticum aestivum ; ×Triticosecale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of water supply on the response of wheat (Triticum aestivum) and triticale (×Triticosecale) to levels of freshly-applied rock phosphate and superphosphate, and the residues of these fertilizers applied 9 years previously in the field, was studied in three glasshouse experiments. The 〈 2 mm fraction of the top 10 cm of soil was used (1.8 kg soil per pot), and in one experiment, freshly-applied fertilizer was also added to the more acidic subsoil (10 to 20 cm). There were two water treatments: the soil was returned to field capacity by watering to weight, either daily (W1, adequate water) or weekly (W2, water stress). Yield of dried tops was used to calculate fertilizer effectiveness. The phosphorus (P) concentration in dried tops was used to determine critical P, which is the P concentration related to 90% of the maximum yield. Just before sowing, soil samples were collected to measure bicarbonate-extractable (soil test) P which was related to plant yield. Water stress reduced yields and maximum yield plateaus by 20 to 40%. Water stress reduced the effectiveness of all P fertilizers by between 20 to 60%, largely because of a reduction in the maximum yield potentials. In the field, water supply is seasonally dependent and it can affect the yield response of plants to freshly-applied rock phosphate and superphosphate and the residues of these fertilizers applied to the field in previous years. Relative to placing fertilizer in the topsoil, placing fertilizer in the subsoil improved effectiveness by about 26% for rock phosphate and 12% for superphosphate. The relationship between yield and P concentration in dried tops, and critical P, differed for W1 and W2. The soil test P calibration, which relates yield to soil test P, and the soil test P required to produce the same yield also differed for W1 and W2. Consequently critical P and soil test P calibrations depend on water supply, which in the field varies within and between growing seasons. This is so for freshly- and previously-applied rock phosphate and superphosphate.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 100 (1994), S. 221-228 
    ISSN: 1432-1939
    Keywords: Triticum aestivum ; Competition ; Abiotic stress ; Multiplicative interactions ; Nickel toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using recently developed solution culture techniques, the effect of a non-resource abiotic stress, nickel toxicity, was tested on intraspecific nutrient competition among wheat. The choice of an appropriate statistical model was of paramount importance in interpreting these effects. We argue that a multiplicative model is more appropriate for experiments on interactions of competition and abiotic stress. By such an analysis, nickel had no relative effect on the ability of competition to reduce plant size in two experiments, and caused a small reduction in competition in another. These results are contrary to other reports of the effect of a non-resource abiotic stress on competition and appear to be due to an increased demand for nutrients in the presence of toxic levels of nickel. The effects of an abiotic stress on competition may thus be specitic to the stress and not generalized across all abiotic stresses.
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  • 4
    ISSN: 1432-2145
    Keywords: Flower ; Meristem ; Gene transfer Particle bombardment ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Direct gene transfer to floral meristems could contribute to cell-fate mapping, to the study of flower-specific genes and promoters, and to the production of transgenic gametes via the transformation of sporogenic tissues. Despite the wide potential of its applications, direct gene transfer to floral meristems has not been achieved so far because of the lack of suitable technology. We show in this paper that ballistic micro-targeting is the technique of choice for this purpose, and in this way, we were able to transfer genes efficiently into excised wheat immature spikes. Particle size was adjusted for optimal penetration into the L1 and L2 cell layers of the spikes with limited cell damage. Spikes at different developmental stages were shot either with a plasmid containing two genes involved in anthocyanin biosynthesis or with a plasmid bearing the uidA (β-glucuronidase) gene. The transient expression of these marker genes was observed in the different developmental stages tested and in cells of both the L1 and the L2 layers. The transient expression of the uidA gene was significantly increased when the sucrose concentration in the culture medium was increased from 0.06 to 0.52 M. At the highest concentration, 100% of the targeted spikes expressed the uidA gene, with an average of 69 blue cells per spike. Twelve days after microtargeting, multicellular sectors showing transgene expression and containing up to 17 cells were found in 85% of the shot immature inflorescences. This indicated that targeted cells survived particle bombardment. Sectors were found in primordia of both vegetative and reproductive organs.
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  • 5
    ISSN: 1432-0983
    Keywords: Reciprocal recombination ; Mitochondrial genome ; Chondriome variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mitochondrial genome of the selfed progeny of a plant regenerated from long-term somatic tissue culture displays specific structural rearrangements characterized by the appearance of novel restriction fragments. A mitochondrial DNA library was constructed from this selfed progeny in the SalI site of cosmid pHC79 and the novel fragments were subsequently studied. They were shown to arise from reciprocal recombination events involving DNA sequences present in the parental plant. The regions of recombination were sequenced and the nucleotide sequences were aligned with those of the presumptive parental fragments. We characterized an imperfect short repeated DNA sequence, 242 bp long, within which a 7-bb DNA repeat could act as a region of recombination. The use of PCR technology allowed us to show that these fragments were present in both parental plants and tissue cultures as low-abundance sequence arrangements.
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  • 6
    Electronic Resource
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    Springer
    Biology and fertility of soils 17 (1994), S. 232-236 
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction ; Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effects of 15N-labelled ammonium nitrate and urea on the yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L., cv. Mexi-Pak-65) in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 33.6–51.5 and 30.5–40.9% of the N from ammonium nitrate and urea, respectively. Splitting the fertilizer N application had a significant effect on the uptake of fertilizer N by the wheat. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the two N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied according to the fertilizer N split; six split applications gave the highest added N interaction compared to a single application or two split applications for both fertilizers. Ammonium nitrate gave 90.5, 33.5, and 48.5% more added N interaction than urea with one, two, and six split N applications. A values were not significantly correlated with the added N interaction (r=0.557). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N replaced unlabelled soil N.
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  • 7
    ISSN: 1573-5028
    Keywords: β-tubulin ; microtubules ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four different β-tubulin coding sequences were isolated from a cDNA library prepared from RNA from maize seedling shoots. The four genes (designated tub4, tub6, tub7 and tub8) represented by these cDNA clones together with the tub1 and tub2 genes reported previously encode six β-tubulin isotypes with 90–97.5% amino acid sequence identity. Results from phylogenetic analysis of 17 β-tubulin genes from monocot and dicot plant species indicated that multiple extant lines of β-tubulin genes diverged from a single precursor after the appearance of the two major subfamilies of α-tubulin genes described previously. Hybridization probes from the 3′ non-coding regions of six β-tubulin clones were used to quantify the levels of corresponding tubulin transcripts in different maize tissues including developing anthers and pollen. The results from these dot blot hybridization experiments showed that all of the β-tubulin genes were expressed in most tissues examined, although each gene showed a unique pattern of differential transcript accumulation. The tub1 gene showed a high level of transcript accumulation in meristematic tissues and almost no accumulation in the late stages of anther development and in pollen. In contrast, the level of tub4 transcripts was very low during early stages of male flower development but increased markedly (more than 100 times) during the development of anthers and in pollen. Results from RNAse protection assays showed that this increased hybridization signal resulted from expression of transcripts from one or two genes closely related to tub4. The tub4-related transcripts were not present in shoot tissue. Transcripts from the tub2 gene accumulated to very low levels in all tissues examined, but reached the highest levels in young anthers containing microspore mother cells. RNAse protection assays were used to measure the absolute levels of α- and β-tubulin transcripts in seedling shoot and in pollen. The α-tubulin gene subfamily I genes (tua1, tua2, tua4) contributed the great majority of α-tubulin transcripts in both shoot and pollen. Transcripts from the β-tubulin genes tub4, tub6, tub7, and tub8 were predominant in shoot, but were much less significant than the tub4-related transcripts in pollen.
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  • 8
    Electronic Resource
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    Springer
    Plant molecular biology 24 (1994), S. 449-463 
    ISSN: 1573-5028
    Keywords: AU-rich ; intron ; maize ; splicing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant introns are generally short (〈200 nt) and AU-rich, and an elevated AU content is necessary for efficient splicing. Further, an intron in some plant genes enhances gene expression by a post-transcriptional mechanism that results in an increase of cytoplasmic mRNA. The specific intron features responsible for efficient splicing and enhancement are not well characterized in plants. Internal deletions of up to 80% of two maize introns, Adh1 intron 1 and maize actin intron 3, indicate that large segments of these introns are dispensable for normal function. However, extensive deletion (〉75%) of Adh1 intron 1 diminishes both intron enhancement and splicing efficiency. This finding suggests that there are internal sequence motifs required for intron function, and that these motifs are redundant. We attempted to repair a deletion-impaired Adh1 intron 1 variant by adding back either oligomers of defined sequence content or fragments of maize internal intron sequence. The addition of AU-rich oligomers improved splicing efficiency and in one example, a U-rich oligomer activated a cryptic 3′ splice acceptor. We also found that replacing the region proximal to the Adh1 intron 1 3′ acceptor with U-rich sequence improved splicing. We found that adding G- and C-rich oligomers did not improve intron function, but a C-rich oligomer activated a cryptic 3′ acceptor. The addition of internal intron sequence to an impaired intron improved splicing, and in one case, resulted in the activation of a cryptic 3′ acceptor. We present evidence that U-rich sequence immediately upstream of the 3′ splice junction increases splicing efficiency and contributes to, but does not uniquely specify, 3′ acceptor AG choice.
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  • 9
    ISSN: 1573-5028
    Keywords: C4 photosynthesis ; maize ; plastid gene expression ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transcription of plastome-encoded genes in mesophyll and bundle-sheath chloroplasts of the monocotyledonous NADP-malic enzyme-type C4 species Zea mays L. (maize) and Sorghum bicolor (L.) Moench. was investigated. RNA accumulation and transcription were assayed starting from isolated mesophyll and bundle-sheath chloroplasts and using quantitative northern and run-on transcription analysis. Determination of the mesophyll to bundle-sheath ratios of transcript abundance in maize and Sorghum chloroplasts showed that the mRNAs of the plastome-encoded photosystem II genes analysed (psbA, psbB, psbD, psbH and psbE/F) varied from 2.5- to 4.0-fold (maize) and 3.1- to 5.2-fold (Sorghum), respectively. The rbcL transcript, in contrast, was more abundant in bundle-sheath chloroplasts of both species, about 3-fold in maize and more than 10-fold in Sorghum. On the other hand, transcripts of genes encoding the 16S ribosomal RNA (r16) and subunits of photosystem I (psaA) and the cytochrome b/f complex (petB, petA) accumulated to similar levels in both types of chloroplasts. Determination of absolute transcript levels for rbcL and psbA in chloroplasts from maize and Sorghum demonstrated that for both genes, the mesophyll to bundle-sheath differences in transcript abundance were more pronounced in Sorghum. Measurements of the transcriptional activities of rbcL and psbA showed that the transcription rate of rbcL is higher in bundle-sheath chloroplasts while psbA is more actively transcribed in mesophyll chloroplasts. The differences in the transcription rates between the two chloroplast types were again more pronounced in Sorghum, thus reflecting the differences between maize and Sorghum in the relative levels of the rbcL and psbA transcripts. However, although transcription rate and mRNA abundance are correlated, they did not exactly match one another. This indicates additional regulation of transcript abundance at the level of RNA stability.
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  • 10
    ISSN: 1573-5028
    Keywords: Cell biology ; epigenetics ; maize ; transformation ; transgenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zea mays transformants produced by particle bombardment of embryogenic suspension culture cells of the genotype A188 × B73 and selected on kanamycin or bialaphos were characterized with respect to transgene integration, expression, and inheritance. Selection on bialaphos, mediated by thebar orpat genes, was more efficient than selection on kanamycin, mediated by thenptII gene. Most transformants contained multicopy, single locus, transgene insertion events. A transgene expression cassette was more likely to be rearranged if expression of that gene was not selected for during callus growth. Not all plants regenerated from calli representing single transformation events expressed the transgenes, and a non-selectable gene (uidA) was expressed in fewer plants than was the selectable transgene. Mendelian inheritance of transgenes consistent with transgene insertion at a single locus was observed for approximately two thirds of the transformants assessed. Transgene expression was typically, but not always, predictable in progeny plants-transgene silencing, as well as poor transgene transmission to progeny, was observed in some plant lines in which the parent plants had expressed the transgene.
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  • 11
    ISSN: 1573-5028
    Keywords: cDNA clones ; EST sequencing ; maize ; RFLP mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As one component of a maize genome project, we report the analysis of a number of randomly selected cDNAs, by a combination of measuring mRNA expression, ‘single-pass’ sequencing (SPS), and genome mapping. Etiolated seedling (490) and membrane-free polysomal endosperm cDNA clones (576) were evaluated for their transcription levels by hybridizing with a probe prepared from total mRNA and categorized as corresponding to abundantly or rarely expressed mRNAs and as either constitutive or tissue-specific. A total of 313 clones from the two libraries were submitted to ‘single-pass’ sequencing from the presumed 5′ end of the mRNA and the nucleotide sequence compared with the GenBank database. About 61% of the clones showed no significant similarities within GenBank, 14% of the clones exhibited a high degree of similarity, while the remaining 25% exhibited a lesser degree of similarity. The chromosomal location of more than 300 clones was determined by RFLP mapping using standard populations. The results demonstrate that a combination of analyses provides synergistic information in eventually deducing the actual function of these types of clones.
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  • 12
    ISSN: 1573-5028
    Keywords: Calvin cycle genes ; gene expression ; SBPase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the isolation and nucleotide sequence of genomic clones encoding the chloroplast enzyme sedoheptulose-1,7-bisphosphatase (SBPase) from Arabidopsis thaliana. The coding region of this gene contains eight exons (72–76 bp) and seven introns (75–91 bp) and encodes a polypeptide of 393 amino acids. Unusually, the 5′ non-coding region contains two additional AUG codons upstream of the translation initiation codon. A comparison of the deduced Arabidopsis and wheat SBPase polypeptide sequences reveals 78.6%, identity. Expression studies showed that the level of SBPase mRNA in Arabidopsis and wheat is regulated in a light-dependent manner and is also influenced by the developmental stage of the leaf. Although the Arabidopsis SBPase gene is present in a single copy, two hybridizing transcripts were detected in some tissues, suggesting the presence of alternate transcription start sites in the upstream region.
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  • 13
    ISSN: 1573-5028
    Keywords: cell cycle ; maize ; non-systemic expression ; polyubiquitin gene ; stress response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used the promoter, 1st exon and 1st intron of the maize polyubiquitin gene (Ubi-1) for rice transformation experiments and revealed the characteristic expression of Ubi-1 gene: (1) Ubi-1 gene is not regulated systemically but rather individual cells respond independently to the heat or physical stress; (2) Ubi-1 gene changes its tissue-specific expression in response to stress treatment; (3) the expression of Ubi-1 gene is dependent on cell cycle.
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  • 14
    ISSN: 1573-5028
    Keywords: maize ; 1-acyl-sn-glycerol-3-phosphate acyltransferase ; complementation cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We selected cDNA plasmid clones that corrected the temperature-sensitive phenotype of Escherichia coli strain JC201, which is deficient in 1-acyl-sn-glycerol-3-phosphate acyltransferase activity. A plasmid-based maize endosperm cDNA library was used for complementation and a plasmid that enabled the cells to grow at 44°C on ampicillin was isolated. Addition of this plasmid (pMAT1) to JC201 restored 1-acyl-sn-glycerol-3-phosphate acyltransferase activity to the cells. Total phospholipid labelling showed that the substrate for the enzyme, lysophosphatidic acid, accumulated in JC201 and was further metabolised to phosphatidylethanolamine in complemented cells. Membranes isolated from such cells were able to convert lysophosphatidic acid to phosphatidic acid in acyltransferase assays. The cDNA insert of pMAT1 contains one long open reading frame of 374 amino acids which encodes a protein of relative molecular weight 42 543. The sequence of this protein is most similar to SLC1, which is thought to be able to acylate glycerol at the sn-2 position during synthesis of inositol-containing lipids. Homologies between the SLC1 protein, the 1-acyl-sn-glycerol-3-phosphate acyltransferase of E. coli (PlsC) and the maize ORF were found with blocks of conserved amino acids, whose spacing was conserved between the three proteins, identifiable.
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  • 15
    ISSN: 1573-5028
    Keywords: intron ; maize ; splicing ; vectors ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms of intron recognition and processing have been well-studied in mammals and yeast, but in plants the biochemistry of splicing is not known and the rules for intron recognition are not clearly defined. To increase understanding of intron processing in plants, we have constructed new pairs of vectors, pSuccess and pFail, to assess the efficiency of splicing in maize cultured cells. In the pFail series we use translation of pre-mRNA to monitor the amount of unspliced RNA. We inserted an ATG codon in the Bz2 (Bronze-2) intron in frame with luciferase: this construct will express luciferase activity only when splicing fails. In the pSuccess series the spliced message is monitored by inserting an ATG upstream of the Bz2 intron in frame with luciferase: this construct will express luciferase activity only when splicing succeeds. We show here, using both the wild-type Bz2 intron and the same intron with splice site mutations, that the efficiency of splicing can be estimated by the ratio between the luciferase activities of the vector pairs. We also show that mutations in the unique U-rich motif inside the intron can modulate splicing. In addition, a GC-rich insertion in the first exon increases the efficiency of splicing, suggesting that exons also play an important role in intron recognition and/or processing.
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  • 16
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    Theoretical and applied genetics 88 (1994), S. 97-101 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; T. speltoides ; Meiotic chromosome pairing ; Alien transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diploid-like chromosome pairing in polyploid wheat is controlled by several Ph (pairing homoeologous) genes with major and minor effects. Homoeologous pairing occurs in either the absence of these genes or their inhibition by genes from other species (Ph I genes). We transferred Ph I genes from Triticum speltoides (syn Aegilops speltoides) to T. aestivum, and on the basis of further analysis it appears that two duplicate and independent Ph I genes were transferred. Since Ph I genes are epistatic to the Ph genes of wheat, homoeologous pairing between the wheat and alien chromosomes occurs in the F1 hybrids. Using the Ph I gene stock, we could demonstrate homoeologous pairing between the wheat and Haynaldia villosa chromosomes. Since homoeologous pairing occurs in F1 hybrids and no cytogenetic manipulation is needed, the Ph I gene stock may be a versatile tool for effecting rapid and efficient alien genetic transfers to wheat.
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  • 17
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    Theoretical and applied genetics 88 (1994), S. 30-32 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; DNase ; Nuclease ; Cytogenetics ; Gene mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA-degrading enzymes of 24.0 kDa and 27.0 kDa were observed to have different activities in two common wheat (Triticum aestivum L.) cultivars, ‘Wichita’ and ‘Cheyenne’. A substrate-based SDS-PAGE assay revealed that these two enzymes were much more active in ‘Wichita’ than in ‘Cheyenne’. Genes controlling the activities of these two enzymes were localized on chromosome 2D by testing DNA-degrading activities in reciprocal chromosome substitution lines between ‘Wichita’ and ‘Cheyenne’. While the allele on ‘Wichita’ chromosome 2D stimulated the activities of the 24.0- and 27.0-kDa enzymes in Cheyenne, the allele on ‘Cheyenne’ chromosome 2D did not reduce the activities of the 24-kDa and 27-kDa enzymes in ‘Wichita’. Whether these genes code for the DNA-degrading enzymes themselves or for factors that regulate the enzyme activities remains unknown.
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  • 18
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    Theoretical and applied genetics 89 (1994), S. 787-793 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Ustilago tritici ; Alien substitution ; Molecular marker ; Gene location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Many genes have been located in wheat chromosomes, yet little is known about the location of genes for resistance to Ustilago tritici, which causes loose smut. Crosses were made between the loose smut susceptible alien substitution lines Cadet 6Ag(6A) and Rescue 6Ag(6A) (lines in which Agropyron chromosome 6 is substituted by wheat chromosome 6A) and four cultivars resistant to U. tritici race T19: ‘Cadet’, ‘Kota’, ‘Thatcher’ and ‘TD18’. The segregating progeny were tested for reaction to race T19 and for the level of binding with a monoclonal antibody specific to a chromosome 6A-coded seed protein. The antibody, which does not bind to seed protein extracts in the absence of the 6A chromosome, was used as a chromosome marker. An association was established between resistance to race T19 and the presence of chromosome 6A for each of the cultivars tested, indicating that resistance to race T19 resides in chromosome 6A. Ustilago tritici race T19 resistance in ‘Cadet’ appears to be located in the short arm of chromosome 6A, based on the evaluation of the Cadet 6A long ditelosomic stock, which was susceptible, and the Cadet 6A-short: 6-Agropyron- short alien translocation stock, which was resistant.
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  • 19
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    Theoretical and applied genetics 87 (1994), S. 821-828 
    ISSN: 1432-2242
    Keywords: RFLP ; Tissue culture ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Total DNAs of plants regenerated from immature embryo-derived 2-month-old embryogenic calli of wheat (cultivars Florida 302, Chris, Pavon, RH770019) were probed with six maize mitochondrial genes (atpA, atp6, apt9, coxI, coxII, rrn18-rrn5), three hypervariable wheat mitochondrial clones (K′, K3, X2), five random pearl millet mitochondrial clones (4A9, 4D1, 4D12, 4E1, 4E11) and the often-used wheat Nor locus probe (pTA71), in order to assess the molecular changes induced in vitro. In addition, protoplast-derived plants, and 24-month-old embryogenic and non-embryogenic calli and cell suspension cultures of Florida 302 were also analyzed. No variation was revealed by the wheat or millet mitochondrial clones. Qualitative variation was detected in the nonembryogenic suspension culture by three maize mitochondrial genes (coxI, rrn18-rrn5, atp6). A callus-specific 3.8-kb Hind III fragment was detected in all four cultivars after hybridization with the coxI gene. The organization of the Nor locus of the plants regenerated from Florida 302 and Chris was stable when compared to their respective control plants and calli. The Nor locus in regenerants of Pavon and RH, on the other hand, was found to be variable. However, Nor locus variability was not observed in 14 individual seed-derived control plants from either Pavon or RH sources. In Pavon, a 3.6-kb Taq I or a 5.6-kb Bam HI+ Eco RI fragment was lost after regeneration. In one of the RH regenerants, which lost a fragment, an additional fragment was observed.
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  • 20
    ISSN: 1432-2242
    Keywords: Leaf rust ; RAPD ; RFLP ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Near-isogenic lines (NILs) for the leaf rust resistance gene Lr9 were screened for polymorphisms at the molecular level. RAPD (random amplified polymorphic DNA) primers as well as RFLP (restriction fragment length polymorphism) markers were used. Out of 395 RAPD primers tested, three showed polymorphisms between NILs, i.e., an additional band was found in resistant lines. One of these polymorphic bands was cloned and sequenced. Specific primers were synthesized, and after amplification only resistant lines showed an amplified product. Thus, these primers define a sequence-tagged site that is specific for the translocated fragment carrying the Lr9 gene. A cross between a resistant NIL and the spelt (Triticum spelta) variety ‘Oberkulmer’ was made, and F2 plants were analyzed for genetic linkage. All three polymorphisms detected by the PCR (polymerase chain reaction) and one RFLP marker (cMWG684) showed complete linkage to the Lr9 gene in 156 and 133 plants analyzed, respectively. A second RFLP marker (PSR546) was closely linked (8±2.4 cM) to the Lr9 gene and the other four DNA markers. As this marker maps to the distal part of the long arm of chromosome 6B of wheat, Lr9 and the other DNA markers also map to the distal region of 6BL. All three PCR markers detected the Lr9 gene in independently derived breeding lines and varieties, thus proving their general applicability in wheat breeding programs.
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  • 21
    ISSN: 1432-2242
    Keywords: RFLP ; Sr22 ; Triticum aestivum ; T. boeoticum ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of the bread wheat variety Schomburgk, and related lines in its pedigree, identified RFLP markers associated with the segment of chromosome 7A carrying the Sr22 gene derived from the diploid species T. boeoticum. The distribution of the RFLP markers indicated that at least 50% of 7AS and 80% of 7AL in Schomburgk is of T. boeoticum origin. Evaluation of five sets of nearisogenic lines, backcross lines in 20 different genetic backgrounds and an F2 population segregating for Sr22 demonstrated a very low level of recombination between the 7A chromosomes of T. boeoticum and T. aestivum. Several recombinants carrying Sr22 but with a much reduced segment of T. boeoticum were identified and these may prove useful in the breeding of further varieties with Sr22.
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  • 22
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Agropyron cristatum ; Alien addition ; RFLP ; Non-radioactive labelling
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    Topics: Biology
    Notes: Abstract A non-radioactive digoxigenin-labelled DNA method was used successfully to identify RFLP markers in 54 Triticum aestivum cv ‘Chinese Spring’ — Agropyron cristatum (2n=28, genome PPPP) P-genome monosomic addition lines. Southern analysis using a set of 14 DNA probes identifying each homoeologous chromosome arm, combined with two restriction enzymes HindIII and EcoRI, indicated that six A. cristatum chromosomes (1P, 2P, 3P, 4P, 5P and 6P) and five A. cristatum chromosome arms (2PS, 2PL, 5PL, 6PS and 6PL) have been individually added to the wheat genome. The added chromosomes of three lines were Agropyron translocated chromosomes. It was also found that two addition plants possessed an Agropyron-wheat translocation. These results showed that RFLP analysis using the set of assigned wheat probes was a powerful tool in detecting and establishing homoeology of alien A. cristatum chromosomes, or arms, added to wheat, as well as in screening the alien addition material. The creation of the monosomic addition lines should be useful for the transfer of disease-resistance genes from A. cristatum to wheat.
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  • 23
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    Theoretical and applied genetics 89 (1994), S. 927-930 
    ISSN: 1432-2242
    Keywords: Restriction fragment length polymorphism ; CCN ; Genetic mapping ; Triticum aestivum ; Heterodera avenae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cereal cyst nematode (CCN) (Heterodera avenae Woll.) is an economically damaging pest of wheat in many of the worlds cereal growing areas. The development of CCN-resistant cultivars may be accelerated by the use of molecular markers. The Cre gene of the wheat line “AUS 10894” confers resistance to CCN. Using a pair of near-isogenic lines (NILs) that should differ only in a small chromosome segment containing the Cre locus, we screened 58 group-2 probes and found two (Tag605 and CDO588) that detect polymorphism between the NILs. Nulli-tetrasomic and ditelosomic lines confirmed that the restriction fragment length polymorphism (RFLP) markers identified were derived from the long arm of wheat chromosome 2. Crosses between “AUS 10894” and “Spear” and the NIL “AP” and its recurrent parent “Prins” were used to produce F2 populations that gave the expected 3∶1 segregation ratio for the resistance gene. Linkage analysis identified two RFLP markers flanking the resistance gene. Xglk605 and Xcdo588 mapped 7.3 cM (LOD=6.0) and 8.4 cM (LOD=6.7), respectively, from the Cre locus.
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  • 24
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    Theoretical and applied genetics 89 (1994), S. 179-184 
    ISSN: 1432-2242
    Keywords: Waxy (Wx) protein ; Triticum aestivum ; Null allele ; Geographical distribution ; Chromosomal location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deficiency of the wheat waxy (Wx) proteins (Wx-A1, Wx-B1 and Wx-D1) was studied in 1,960 cultivars derived from several countries. Gel electrophoretic analyses revealed that the null allele for the Wx-A1 protein occurred frequently in Korean, Japanese and Turkish wheats but was relatively rare in cultivars from other countries and regions. About 48% of the wheats deficient for the Wx-B1 protein were from Australia and India. One Chinese cultivar lacked the WxD1 protein. While 9 Japanese cultivars were deficient in both the Wx-A1 and Wx-B1 proteins, no cultivars lacked both the Wx-A1 and Wx-D1 proteins, both the Wx-B1 and Wx-D1 proteins or all three Wx proteins. Two-dimensional gel electrophoresis revealed polymorphisms of the three Wx proteins that varied according to isoelectric points or molecular weight. The Wx-A1 gene coding the Wx-A1 protein and the Wx-B1 gene coding the Wx-B1 protein were localized in the distal regions of chromosome arms 7AS and 4AL, respectively, by deletion mapping using the deletion lines developed in the common wheat cultivar ‘Chinese Spring’.
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  • 25
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    Theoretical and applied genetics 89 (1994), S. 276-280 
    ISSN: 1432-2242
    Keywords: Amylose content ; Monosomic ; Substitution line ; Triticum aestivum ; Wx protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The endosperm starch of the wheat grain is composed of amylose and amylopectin. Genetic manipulation of the ratio of amylose to amylopectin or the amylose content could bring about improved texture and quality of wheat flour. The chromosomal locations of genes affecting amylose content were investigated using a monosomic series of Chinese Spring (CS) and a set of Cheyenne (CNN) chromosome substitution lines in the CS genetic background. Trials over three seasons revealed that a decrease in amylose content occurred in monosomic 4A and an increase in monosomic 7B. Allelic variation between CS and CNN was suggested for the genes on chromosomes 4A and 7B. To examine the effects of three Waxy (Wx) genes which encode a granule-bound starch synthase (Wx protein), the Wx proteins from CS monosomics of interest were analyzed using SDS-PAGE. The amount of the Wx protein coded by the Wx-B1 gene on chromosome arm 4AL was reduced in monosomic 4A, and thus accounted for its decreased amylose content. The amounts of two other Wx proteins coded by the Wx-A1 and Wx-D1 genes on chromosome arms 7AS and 7DS, respectively, showed low levels of protein in the monosomics but no effect on amylose content. The effect of chromosome 7B on the level of amylose suggested the presence of a regulator gene which suppresses the activities of the Wx genes.
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  • 26
    ISSN: 1573-9368
    Keywords: C4-plant ; maize ; phosphoenolpyruvate carboxylase ; quantum yield ; transgenic tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of maize (Zea mays) phosphoenolpyruvate carboxylase (PEPC) gene constructs in transgenic tobacco plants (Nicotiana tabacum) was studied. Where transcription was under the control of a CaMV 35S promoter, maize PEPC transcripts of the correct size were detected. Western blot analysis indicated that the transgenic plants contained about twice as much PEPC as non-transformed plants. Furthermore, the enzymatic activity of PEPC in the leaves of these transgenic plants was up to twice as high as that in non-transformed plants. Two forms of PEPC with different kinetic properties were identified in leaf extracts of the transgenic plants: one form (the maize isoform) gave a high apparentK m value for phosphoenolpyruvate (PEP) and a high maximum activity, and the other (the tobacco isoform) exhibited a low apparentK m value for PEP and a low maximum activity. These biochemical differences resulted in several significant physiological changes in the transgenic plants: (1) the growth rate of the transgenic plants was lower than that of non-transgenic plants: (2) chlorophyll content per leaf area was relatively lower in the transgenic plants; and (3) the quantum yield of photosynthesis in the transgenic plants was not affected by changes in leaf temperature.
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  • 27
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    Protoplasma 178 (1994), S. 81-85 
    ISSN: 1615-6102
    Keywords: Adenosine triphosphate ; Anaerobiosis ; Fluorescein-dextrans ; Plasmodesmata ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell-to-cell transport of small molecules and ions occurs in plants through plasmodesmata. Plant roots are frequently subjected to localized anaerobic stress, with a resultant decrease in ATP. In order to determine the effect of this stress on plasmodesmal transport, fluorescent dyes of increasing molecular weight (0.46 to 10 kDa) were injected into epidermal and cortical cells of 3-day-old wheat roots, and their movement into neighboring cells was determined by fluorescence microscopy. Anaerobiosis was generated by N2 gas or simulated by the presence of sodium azide, both of which reduced the ATP levels in the tissue by over 80%. In the absence of such stress, the upper limit for movement, or size exclusion limit (SEL), of cortical plasmodesmata was 〈1 kDa. The ATP analogue TNP-ADP (mw 681) moved across the plasmodesmata of unstressed roots, indicating that plasmodesmata may be conduits for nucleotide (ATP and ADP) exchange between cells. Upon imposition of stress, the SEL rose to between 5 and 10 kDa. This response of plasmodesmata to a decrease in the level of ATP suggests that they are constricted by an ATP-dependent process so as to maintain a restricted SEL. When roots are subjected to anaerobic stress, an increase in SEL may permit enhanced delivery of sugars to the affected cells of the root where anaerobic respiration could regenerate the needed ATP.
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  • 28
    ISSN: 1573-8469
    Keywords: wheat ; Triticum aestivum ; oat ; Avena sativa ; barley ; Hordeum vulgare ; serology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Various modifications of the tissue-blot immunoassay (TBIA) for the detection of barley yellow dwarf virus (BYDV, luteovirus) were compared. Similar results were obtained by using three different labelled molecules; goat anti-rabbit antibodies conjugated to alkaline phosphatase, protein A conjugated with alkaline phosphatase and goat anti-rabbit antibodies conjugated with colloidal gold. Blocking the nitrocellulose membrane with polyvinyl alcohol for 1 min was effective and allowed the procedure to be shortened by one hour. TBIA was sensitive enough to detect BYDV in old dry tissue wich had been soaked in water for 1 h. BYDV was monitored by TBIA in wheat, oat and barley after inoculation at heading, flowering and grain filling growth stages. The later the inoculation date, the greater the chance of detecting the virus in stem bases rather than in the upper part of the stem. The later the inoculation the less virus moved, from the inoculated tiller to other tillers of the same plant.
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  • 29
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    Plant and soil 162 (1994), S. 309-313 
    ISSN: 1573-5036
    Keywords: in vitro translation ; maize ; nutrient stress proteins ; Poly(A)+RNA ; sulphate deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots of ten-days-old seedlings obtained from a maize hybrid grown in complete or in sulphate-deprived medium were used to extract Poly(A)+RNA. The response to sulphate deprivation, which is known to increase the uptake capacity up to ten times, was manifested also by the expression of three mRNA species, as shown by the in vitro translation of the mRNA population. One hour after transfer to complete nutrient medium all three mRNAs were still present.
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  • 30
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    Plant and soil 165 (1994), S. 327-332 
    ISSN: 1573-5036
    Keywords: gravitropism ; maize ; nodal roots ; plagiogravitropism ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth can be studied by analyzing the trajectories of roots growing in soil. Both the primary seminal root and nodal roots of maize attain a preferred, or liminal, angle of growth that deviates from the vertical. These roots are said to be plagiogravitropic. Experiments using plants grown in soil-filled boxes revealed that the primary seminal root is truly plagiogravitropic. It shows both positive and negative gravitropism in response to gravity stimuli and tends to maintain its direction even after growing around obstacles. These are experimental results suggesting that plagiogravitropic growth is controlled by internal factors. The orientation of the grain affects the establishment of the liminal angle of the primary seminal root, and both the position of their node of origin and the root diameter are closely related to the plagiogravitropic behaviour of nodal roots. Several external factors are also known to influence plagiogravitropism. Low soil water content causes a decrease in the angle of growth and soil mechanical resistance suppresses the gravitropic curvature. Plagiogravitropic behaviour of both seminal and nodal roots plays a significant role in shaping the root system.
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  • 31
    ISSN: 1573-5060
    Keywords: abscisic acid ; inheritance ; drought stress ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study analyzes the components of phenotypic variation for abscisic acid (ABA) content in maize (Zea mays L.) leaves and the correlations with drought sensitivity index (DSI) and silk delay (SD), involved in the reaction to water deficit. Eight early- and seven medium-maturity inbreds were examined in field trials: in 1990 with low irrigation volume and in 1991 with low and high irrigation volumes. ABA concentration and DSI were investigated at growth stages (S) corresponding to stem elongation (S3), appearance of the first husks (S4), and mid-end of silking (S5). The ABA concentration was significantly higher in conditions of water deficit and in the later growth stage. The genetic component for ABA concentration attained higher relative values than those shown by DSI in the same growth stages and by SD; moreover, it increased from growth stage 3 to stage 5. The genotype × year and genotype × irrigation volume interactions were smaller for ABA concentration than for DSI and SD. The broad sense heritability on a plant basis, estimated in drought conditions, for ABA concentration ranged from 21.4 to 55.1% according to maturity group and growth stage. A wide variation was observed among lines for ABA concentration: the medium-maturity group showed a three-fold range (from 219 to 605 ng ABA g−1 dry weight). No clear relationships between ABA concentration, DSI and SD were found. These results indicate the feasibility of a selection for ABA concentration within segregating populations derived from crosses between the inbred lines herein tested.
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  • 32
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; genetic basis ; grain filling rate ; genetic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P 〈 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P 〈 0.001) in LE and WPE. It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.
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  • 33
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    Euphytica 76 (1994), S. 53-61 
    ISSN: 1573-5060
    Keywords: stripe rust ; stem rust ; leaf rust ; powdery mildew ; common wheat ; environmental effects ; Puccinia striiformis ; Puccinia graminis ; Puccinia recondita ; Erysiphe graminis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of rust resistances conferred by closely linked genes derived from VPM1 varied with environmental conditions and with genetic backgrounds. Under low light and low temperature conditions seedlings carrying Yr17 showed susceptible responses. Stem rust and leaf rust resistance genes Sr38 and Lr37 tended to confer more resistance at 17±2° C than at normal temperatures above 〉 20° C. These studies supported the hypothesis that Yr17, Lr37 and Sr38 were derived from Aegilops ventricosa, whereas Pm4b was probably derived from T. persicum. Studies on certain addition lines and parental stocks indicated that wheat cytoplasm may enhance the expression of Sr38.
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  • 34
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    Photosynthesis research 39 (1994), S. 427-438 
    ISSN: 1573-5079
    Keywords: acetate ; glucose ; maize ; metabolic repression ; photosynthetic genes ; transcription regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although feedback regulation of photosynthesis by carbon metabolites has long been recognized and investigated, its underlying molecular mechanisms remain unclear. The recent discovery that glucose and acetate trigger global repression of maize photosynthetic gene transcription provides the first direct evidence that a fundamental mechanism is used for feedback regulation of photosynthesis in higher plants. The metabolic repression of photosynthetic genes has now been found in many higher plants and is likely universal. It overrides other regulation by light, tissue type and developmental stage, and serves potentially as the molecular basis of interactions between sink and source tissues. Using simplified and convenient cellular systems and transgenic plants, the study of metabolic regulation of gene expression offers an excellent opportunity for the understanding of global and coordinate gene control and metabolite-mediated signal transduction in higher plants.
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  • 35
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    Plant and soil 164 (1994), S. 155-167 
    ISSN: 1573-5036
    Keywords: axile roots ; maize ; nodal roots ; root length ; root system ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to study elongation curves of maize axile roots throughout their elongation period under field conditions. Relationships between their elongation rate and the extension rate of their branched region were also studied. Maize, early-maturing cultivar Dea, was grown on a deep, barrier-free clay loam (depth 1.80m). Trenches were dug during four periods until after silking and axile roots were excavated. Parameters measured were total length and the lengths of basal and apical unbranched zones. The rank of the bearing phytomer and general data about the carrying plant were also recorded. Results showed that axile roots from lower phytomers had similar elongation rates irrespective of the rank of the carrying phytomer. This elongation rate declined with root age. A monomolecular elongation model was fitted to the experimental data. Elongation was much slower in roots from upper phytomers. A rough linear relationship was found between the elongation rate of axile roots and the length of the apical unbranched zone. This result suggests that laterals appeared on a root segment a constant time after it was formed. Possible mechanisms with may account for the declining elongation rate with root age (increasing distance from aerial parts or adverse environmental conditions in deep soil layers) and variability between individual roots are also discussed.
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  • 36
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    Plant and soil 164 (1994), S. 169-176 
    ISSN: 1573-5036
    Keywords: branching ; growth ; lateral roots ; maize ; root morphology ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The architecture of the root system is related to its water and mineral uptake. In this paper, the number, growth, and branching of first-order lateral roots are studied on field grown maize (early maturing cultivar ‘Dea’), mainly in relation to the depth and to the rank of the bearing phytomer. The soil was a deep clay loam, without any barrier until 1.80 m. The branching density was studied along axile roots until 1.40 m from the base, on a sample of individually excavated axile roots. A strong gradient of density was shown: the mean branching density decreased from 12 roots.cm−1 near the base to 4 roots.cm−1 at a 60 cm depth. Seminal roots were less densely branched than nodal roots. The mean difference was about 4 roots.cm−1. The length and branching density of lateral roots were studied on mature parts of the root systems where the growth and branching of the laterals were completed, using samples extracted from large soil monoliths. The length distribution of lateral roots was highly asymmetrical, for every source phytomer (mean: 25 mm; median: 16 mm). Many lateral roots were very short, and only 2 % reached a length higher than 10 cm. Only 29 % of all the laterals bore second-order lateral roots. Vigorous laterals branched more systematically and more profusely: the branching density varied from 2 to 5 roots.cm−1 according to the length of the mother lateral root. Both the number and length of lateral roots appeared to be affected by the soil bulk density which varied with the depth.
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  • 37
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    Plant and soil 163 (1994), S. 1-12 
    ISSN: 1573-5036
    Keywords: amino-acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of intact Zea mays. L. roots to regulate the amount of free amino-acids present in the rhizosphere. Using metabolic inhibitors it was demonstrated that the release of amino-acids from the root occurred by passive diffusion, whilst free amino-acids outside the root could be re-captured by an active transport mechanism. The influx of amino-acids into the root was shown to be relatively independent of spatial location along the root and was little affected by the presence of other organic compounds in solution. It was deduced from root concentration gradients that the main site of amino-acid exudation was at root tips. Amino-acid uptake by the root was shown to be independent of both inorganic-N concentration and the presence of other organic solutes in solution. A computer simulation model was constructed to assess the contribution of organic-N uptake (acidic, basic and neutral amino-acids) to the plant's N budget, in comparison to the inorganic solutes NO3 and NH4. Simulations of N uptake from a 0.5 mm radius rhizosphere indicated that when inorganic-N concentrations in soil were limiting (≤0.1 μmoles cm-3 soil), the uptake of amino-N accounted for up to 90% the total N taken up by the roots. In situations where fertilizer inputs are high, and levels of organic matter in soil are low, the contribution of amino-N might still be expected to form 〈30% of the total N taken up by the root system. It was concluded that the uptake of amino-acids from the rhizosphere may be important in both N nutrition and in the minimization of root C and N losses to the soil. Consequently this may be important in governing the size of the rhizosphere microbial population.
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  • 38
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    Plant and soil 166 (1994), S. 21-30 
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
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  • 39
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    Euphytica 78 (1994), S. 1-5 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; C-band polymorphism ; structural rearrangements ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Giemsa C-banding allows for the identification of all 21 chromosome pairs of hexaploid wheat. However, variation in banding patterns of individual chromosomes and structural rearrangements exist between different cultivars making chromosome identification more difficult. The paper summarizes the available data on C-band polymorphism and structural rearrangement present in wheat cultivars and germplasms.
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  • 40
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Hordeum vulgare ; barley ; intergeneric hybridization ; influence of temperature ; embryo development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of temperature on seed set and embryo development in reciprocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvásári 50) and one wheat variety (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled environments at constant day-night temperature regimes (12, 15, 18 and 21° C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15° C) produced the maximum seed set, whereas for the reciprocal cross, the highest temperature (21° C) produced the best seed set in the Chinese Spring × Betzes combination. Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18° C and 21° C in the barley × wheat cross and in the wheat × barley cross, respectively. Embryos of about 1.5 mm length in the barley × wheat cross, and of about 1.0 mm length in the wheat × barley cross germinated successfully. The smallest embryo giving rise to hybrid plants was 0.57 mm in the barley × wheat cross and 0.51 mm in the wheat × barley cross.
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  • 41
    ISSN: 1573-5087
    Keywords: auxin-transport ; indoleacetic acid ; maize ; photoinhibition ; transport ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of IAA into excised mesocotyls of non-irradiated maize seedlings was linear up to a concentration of about 4×M and in this range there was a tight coupling between the IAA in the stele and the cortex. Prior irradiation with white light of intact seedlings unbalanced this coupling. Lateral and longitudinal transport were affected differently. In the stele, the effect of prior irradiation on longitudinal transport was multiphasic, with an initial stimulatory effect followed by a negative effect at longer prior irradiation times. The lateral transport from the stele to the cortex showed no stimulatory effect and appeared to be inhibited within at least 15 min. The effect of the prior irradiation on longitudinal transport in the stele appeared to be a high intensity effect. In contrast, the effect of the prior irradiation on the lateral transport from the stele to the cortex was saturated at much lower intensities. The data suggest that the light induced change in the lateral transport of IAA between the two tissues may be due to changes either in the number of open lateral transport channels/carriers or in the conductivity of these channels/carriers.
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  • 42
    ISSN: 1573-5087
    Keywords: homobrassinolide ; irrigated ; membrane stability ; moisture-stress ; nitrate reductase activity ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Homobrassinolide (BR) was applied either as a seed treatment or foliar spray to two contrasting wheat varieties, viz. C306 (drought tolerant) and HD2329 (drought susceptible), to examine its effects on plant metabolism and grain yield under irrigated and moisture-stress/rainfed conditions. BR application resulted in increased relative water content, nitrate reductase activity, chlorophyll content and photosynthesis under both conditions. BR application also improved membrane stability (lower injury). These beneficial effects resulted in higher leaf area, biomass production, grain yield and yield related parameters in the treated plants. All the treatments were significantly better than the untreated control. Generally, 0.05 ppm either as a seed treatment or foliar spray was more effective than the 0.01 ppm treatment. The drought-tolerant genotype C306 showed more response to BR application under moisture-stress/rainfed condition than HD 2329. Increased water uptake, membrane stability and higher carbon dioxide and nitrogen assimilation rates under stress seemed to be related to homobrassinolide-induced drought tolerance.
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  • 43
    ISSN: 1573-6857
    Keywords: isozymes ; Tripsacum ; maize ; wide hybridizations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random samples, consisting of at least 100 individual seedlings, were taken from the diploid (2n=2x=36) eastern gamagrass (Tripsacum dactyloides var.dactyloides) and assayed to determine which of 12 enzyme marker loci and isozyme systems would be most informative in providing satisfactory resolution of both maize andTripsacum isozyme systems. For comparison, eight maize inbreds were included in the study to aid evaluation and comparison of the various isozyme systems. In addition, evaluations were conducted to identify if the identified optimum isozyme system could be used to detectTripsacum introgression in maize following a maize ×Tripsacum backcrossing scheme. Using the established isozyme techniques for maize (Zea mays L.), theAdh, Pgd, Cat, Est, B-Glu, Got, Idh, Tpi isozyme systems detected no polymorphism among theTripsacum individuals assayed. TheEst andB-Glu systems forTripsacum were unscorable due to poor staining and resolution. TheAcp, Mdh, Pgm, andPhi isozyme systems were found to be satisfactory markers for differentiating between eastern gamagrass individuals as well as detectingTripsacum introgression in maize. The availability of useful isozyme systems which can simultaneously provide significant isozyme resolution of maize,Tripsacum and maize-Tripsacum backcross hybrids, on a single gel system, will be useful for the detection of marker assistedTripsacum introgression into maize. In addition, the identification of a set of variable biochemical markers should also assist breeding, selection and genetic manipulations in eastern gamagrass.
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  • 44
    ISSN: 1573-6857
    Keywords: anthocyanin ; maize ; helix-loop-helix ; tissue specificity ; paramutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The red and purple anthocyanin pigments of plants are visible genetic markers and their spatial and temporal accumulation is strictly regulated. Anthocyanin biosynthesis is also modulated by environmental factors such as light and temperature. Thus this process represents an appealing model system for the study of gene regulation, as well as for studying developmental biology. In maize, the pattern of pigmentation of the plant is controlled by theR, Sn andB genes, a small family of HLH transcription factors. Here we report the pattern of light induction and tissue specific expression of the regulatory and structural genes involved in this biosynthesis. TwoSn alleles differing in their light response have been considered and analyzed by Northern andin situ hybridization experiments. An unusual phenomenon of interaction between the homologousR andSn genes leading to a partial gene silencing is reported. We hypothesize a model in which silencing is achieved through methylation of specific sites.
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  • 45
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    Plant growth regulation 15 (1994), S. 107-112 
    ISSN: 1573-5087
    Keywords: aminoethoxyvinylglycine ; ear senescence ; ethephon ; ethylene ; grain maturation ; silver thiosulfate ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This work was aimed at testing the involvement of ethylene in the maturation of grain and senescence of the foliar structures of the wheat inflorescence. Whole wheat ears emitted ethylene to the atmosphere. From pre-anthesis, ethylene emission progressively increased from 0.76 nl g−1FW h−1 to a peak 1.53 nl g−1FW h−1 at the hard dough stage of the grains, to fall to a minimum of 0.10 nl g−1FW h−1 at the dormant seed stage. Ethephon increased the ethylene release, hastened the process of grain maturation and senescence of the ears. Aminoethoxyvinylglycine and silver thiosulfate produced the opposite effects. It is concluded that ethylene plays a role in grain maturation and in the senescence of the green bracts of the inflorescence.
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  • 46
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    World journal of microbiology and biotechnology 10 (1994), S. 410-413 
    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; mawè ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lactic acid bacteria increased from 3.2 × 106 and 1.6 × 107 c.f.u./g (wet wt) to 2 × 109 and 1.6 × 109 c.f.u./g after 12 to 24 h of fermentation of home-produced mawè (a dough produced from dehulled maize) and commercial mawè, respectively. In commercial mawè, the yeast count increased from 1.3 × 105 to 2.5 × 107 c.f.u./g after 48 h of fermentation before decreasing, whereas in the home-produced mawè it increased from 2.5 × 104 to 3.2 × 107 c.f.u./g after 72 h of fermentation; the dominant yeasts were mainly Candida krusei, although C. kefyr, C. glabrata and Saccharomyces cerevisiae were also present. Enterobacteriaceae counts increased slightly during the initial stage ofthe fermentation, but decreased below the detection level after 24 to 48 h. Enterobacter cloacae was mostly found in commercial mawè and Escherichia coli mostly in homeproduced mawè.
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  • 47
    ISSN: 1573-0867
    Keywords: coastal superphosphate ; Ecophos ; North Carolina rock phosphate ; ordinary (single) superphosphate ; partially acidulated rock phosphate (PARP) ; reactive rock phosphate ; relative effectiveness ; residual value ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effectiveness of coastal superphosphate, a partially acidulated rock phosphate (PARP) made from apatite, and Ecophos, a PARP made from calcium iron aluminium (crandallite millisite) rock phosphate, was compared in pot experiments with the effectiveness of ordinary superphosphate (OSP) and North Carolina reactive apatite rock phosphate (NCRP). There were three experiments using different lateritic soils collected in Western Australia. Fertilizer effectiveness was measured using yield of dried wheat (Triticum aestivum) tops grown for 28 days. Three successive crops were grown. The phosphorous (P) fertilizers were applied and mixed with the soils before sowing the first crop. In addition, OSP was added to extra pots before sowing crops 2 and 3 in order to measure the effectiveness of the original P fertilizers relative to freshly-applied OSP for these crops. As measured using plant yield, coastal superphosphate was the most effective P fertilizer for three crops on an acidic peaty sand (pH water 5.0). Relative to freshly-applied OSP, it was 154% as effective for crop 1, 75% as effective for crop 2, and 36% as effective for crop 3. Corresponding values for Ecophos were 44, 29 and 19%, and for NCRP, 77, 67 and 29%, with the original OSP treatment being 61 and 56% as effective for crops 2 and 3. For three crops on a lateritic gravel loam (pH 6.5), both coastal superphosphate and OSP were the most effective fertilizers, and were equally effective for crop 1, and relative to freshly-applied OSP, were about 31% as effective for crop 2, and 16 and 21 % as effective for crop 3. Corresponding values for Ecophos were 47,15 and 11%, and NCRP, 33,15 and 5%. For two crops in a loamy sand (pH 5.4), OSP was the most effective fertilizer, and, relative to fresh OSP, it was 36% as effective for crop 2. Relative to fresh OSP, the effectiveness for crops 1 and 2 of coastal superphosphate was 57 and 18%, for Ecophos 71 and 27%, and for NCRP 50 and 36%.
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  • 48
    ISSN: 1572-9680
    Keywords: alley cropping ; Erythrina poeppigiana ; Gliricidia sepium ; weeds ; maize ; mulch ; weed competition ; weed reduction potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare.
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  • 49
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    Agroforestry systems 26 (1994), S. 249-254 
    ISSN: 1572-9680
    Keywords: phytotoxicity ; cowpea ; Gliricidia sepium prunings ; maize ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phytotoxic effects ofGliricidia prunings were tested on maize seedlings in the laboratory and on maize and cowpea seedlings in the field. In the laboratory test, growth of maize seedlings was significantly depressed by addition of leachate ofGliricidia prunings. In the field, leaf, chlorosis of maize and cowpea seedlings occurred when mulched withGliricidia prunings; number of affected leaves increased with increasing mulch rate. Maize was more susceptible than cowpea. This phytotoxic effect, however, did not reduce growth of maize and cowpea seedlings in the field. ApplyingGliricidia mulch one week before planting eliminated the phytotoxic effects on maize.
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  • 50
    ISSN: 1572-9680
    Keywords: alley cropping ; leucaena mulch ; dairy cattle slurry ; maize ; cowpea ; lowland coastal tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of leucaena hedgerows, mulching with leucaena foliage (0,50 and 100% of harvested foliage), cowpea intercropping and adition of dairy cattle slurry (55 t ha−1 per maize crop) on the yield of maize from a sandy soil were assessed. The four-year results from five maize crops are reported. Except in the first year, yields of maize grain and stover were significantly reduced by 30% in the presence of leucaena hedgerows. Use of leucaena mulch eliminated this effect; application of all the harvested leucaena mulch (100%) increased the total maize grain yield of the five crops by 44% over sole maize. Hedgerow and mulching management required an additional 36 mandays labour ha−1 which was more than compensated by the increased maize yields. Furthermore leucaena hedgerows substantially depressed the growth of weeds between cropping seasons. Intercropping with cowpea significantly depressed yields of maize grain and stover when both crops were sown together, but not in later seasons when cowpea was sown four weeks after the maize. Application of slurry increased the total yields of maize grain and stover by 35 and 37%, respectively. The grain yield of maize in leucaena hedgerow treatments fertilized with slurry did not respond to application of more than 50% of leucaena foliage, which suggested that half of the foliage could be spared for feeding to livestock. The cumulative yield of maize grain from the highest yielding organic system was 85% of the yield from the fertilizer treatment. The study, which is continuing, demonstrates that large increases in agricultural productivity are possible through the intercropping of maize with woody forage and grain legumes and the integration of dairy cattle production into the system. It thus shows the importance of exploiting crop/livestock interactions.
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  • 51
    ISSN: 1573-5109
    Keywords: Aegilops tauschii ; synthetic wheats ; tan spot resistance ; Pyrenophora tritici-repentis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 59 diploid Aegilops tauschii Coss. (syn. Aegilops sguarrosa auct. non L.) and 39 synthetic hexaploid wheat accessions were evaluated for reaction to Pyrenophora tritici-repentis (Died.) Drechs. in a controlled environment, and classified using a disease rating system based on lesion type. 27 Ae. tauschii and 20 synthetic wheats were found to be resistant to tan spot disease. The overall mean disease ratings of Ae. tauschii and the synthetic wheat lines scored on a scale of 1 (resistant) to 5 (susceptible) were 1.80 and 2.38, respectively. Synthetic wheats generally showed a decrease in resistance, although several lines of synthetic wheat expressed a higher resistance than the diploid parents. Five synthetic wheat lines exhibited higher resistance than the standard resistant common wheat cultivar ‘Red Chief’.
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  • 52
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    Genetic resources and crop evolution 41 (1994), S. 151-158 
    ISSN: 1573-5109
    Keywords: Triticum aestivum ; Aegilops tauschii (syn. Ae. squarrosa) ; Erysiphe graminis f. sp. tritici resistance genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A collection of 400 Ae. tauschii (syn. Ae. squarrosa) Coss. accessions were screened for powdery mildew resistance based on the response patterns of 13 wheat cultivars/lines possessing major resistance genes to nine differential mildew isolates. 106 accessions showed complete resistance to all isolates, and 174 accessions revealed isolate-specific resistance, among which were 40 accessions exhibiting an identical response pattern as wheat cultivar ‘Ulka/*8Cc’ which is known to possess resistance gene Pm2. Expression of both complete and isolate-specific resistance from Ae. tauschii was observed in some synthetic hexaploid wheats derived from four mildew susceptible T. durum Desf. parents, each crossed with five to 38 resistant diploid Ae. tauschii accessions. Synthetic amphiploids involving different combinations of T. durum and Ae. tauschii generally showed a decrease in resistance compared with that expressed by the Ae. tauschii parental lines.
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  • 53
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    Euphytica 79 (1994), S. 149-161 
    ISSN: 1573-5060
    Keywords: maize ; germplasm ; cluster analysis ; landraces ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments were carried out with two objectives. First, to establish the phenetic relationships among the maize (Zea mays L.) landraces from Galicia (Northwestern Spain) maintained at the Misión Biológica de Galicia. Second, to assess the resemblance between a collection of Spanish populations (including the landraces from Galicia) and a set of US Corn Belt varieties. For the first objective 73 varieties from Galicia, along with 9 hybrid checks, were grown in 9×9 simple lattices at two locations for two years. For the second objective 131 populations from the US Corn Belt and Spain, along with 9 hybrid checks, were grown for three years in unreplicated experiments. Cluster analyses were carried out with the first principal components that accounted for a significant amount of the total variation. Four groups were found among the landraces from Galicia. The populations from Spain and America were classified as belonging to nine main groups. The replicated experiment was more accurate than the unreplicated one. However, it is concluded that an unreplicated test grown in several environments is accurate enough to detect the main groups, although some inaccuracies should be expected.
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  • 54
    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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  • 55
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    Euphytica 80 (1994), S. 151-155 
    ISSN: 1573-5060
    Keywords: leaf rust resistance ; Puccinia recondita ; Triticum aestivum ; wheat ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The inheritance of leaf rust resistance was studied in 13 accessions of the A.E. Watkins wheat collection. Eight of the accessions (V409, V624, V628, V712, V731, V734, V745, and V855) were shown to have gene Lr33 and four of these (V409, V624, V628, and V731) also have LrW. Accessions V624 and V338 have LrB, and V377 and V488 have Lr11. V46 has an unidentified gene that gives an intermediate level of resistance. V860 has a partially dominant gene that gives a fleck reaction to avirulent isolates in the seedling stage. This gene is different from LrW and may be previously unidentified. It has been assigned the temporary gene symbol LrW2. In addition to seedling-effective genes, V46, V731, and V745 may have Lr34 and V745 may have Lr13. The adult-plant resistance in V488, V624, and V860 could not be identified. Seedling gene LrW2 and some of the adult-plant resistance should be useful sources of resistance.
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  • 56
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia striiformis ; yellow rust ; durable resistance ; race-specific resistance ; residual resistance ; races ; virulence, Kenya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Virulence patterns of yellow rust isolates collected in Kenya between 1986–1989 were compared with earlier results. The number of virulence factors per race and the range in virulence factors both increased considerably. Before 1976 races carried on average 4.5 to 5.0 virulence factors, whereas the races after 1986 had a mean of 6.5 virulence factors. The range in the number of virulence factors increased from some seven to eight in the first period to 12 in the second out of the 17 evaluated. In the period 1986–1989 another three virulence factors (2, 9 and A) were assessed. All three occurred at a high frequency. Virulence neutralizing the resistance genes Yr2, Yr2+, Yr6, Yr6+, Yr7, Yr7+, Yr8, Yr9, Yr9+ and those in the cultivars Anza (A), Strubes Dickkopf (SD) and Suwon92/Omar (SU) occurred at a high frequency, while virulence for Yr3V, Yr4+, Yr5, CV and SP (resistance in Carstens V and Spaldings Prolific resp.) were not found. The remaining three virulence factors for Yr1, 10 and 3N were rare. In the past ten years the resistance of most released cultivars became ineffective in less than six years. They were shown to carry race-specific major resistance genes such as Yr7+, Yr9+, SD and A. However, in the field, the resistance of the cultivars was not completely neutralized. A residual resistance, ranging from moderate to fairly high, was observed in all cultivars in which the major gene resistances were neutralized by corresponding virulence genes. Other wheat cultivars such as Africa Mayo, Kenya Kudu, Enkoy, Kenya Leopard, Bounty, Frontatch, Bonny and Kenya Plume appeared to keep their resistance over a condiserable period of time. They are considered to be durably resistant to the Kenyan yellow rust populations. This form of resistance, together with the residual resistance, can be recommended for use in breeding programmes.
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  • 57
    ISSN: 1573-5036
    Keywords: maize ; P placement ; P supply ; rooting zone ; VAM colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Colonization of plant roots by vesicular-arbuscular mycorrhizal fungi is known to be reduced as the phosphorus nutrition of the plant is increased. It is generally accepted that the concentration of P in the plant rather than the soil regulates VAM colonization. Whether it is the shoot P concentration, the mean P concentration in the root system or the P concentration in the specific root being colonized is not known, but is of agronomic significance because fertilizer P is frequently applied in concentrated zones which would be expected to result in higher P concentration in roots growing in the fertilized zone than in the remainder of the root system. Growth chamber and field experiments were conducted to determine the effect on colonization of supplying varying amounts of P to different portions of the rooting zone. In growth chamber studies using a split-pot technique, the proportion of maize (Zea mays L.) root length containing arbuscules in a high-P zone was lower than that of roots of the same plant growing in a low- or medium-P zone. Root P concentration was higher in the high-P zone. In a field experiment conducted over a two-year period, VAM colonization of roots of young maize plants growing in fertilized soil was affected differently than that of roots growing outside the fertilized zone. A small addition of fertilizer P increased colonization of roots in the fertilized soil, but further additions resulted in an abrupt decline followed by a slower further decline, although colonization was not eliminated even by rates of 1600 μg P g-1 soil. Colonization of roots growing outside the fertilized zone declined gradually with increasing P addition but the overall decline was less than for roots in the fertilized zone. The data support the hypothesis that it is P concentration in the portion of the root system being colonized rather than the general P status of the plant which regulates VAM colonization. The agronomic implication of this is that, although a fertilizer band may reduce VAM colonization of roots in the band volume, roots growing outside this volume may be well colonized so the mycorrhizal symbiosis may be an important contributor to P nutrition.
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  • 58
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    Plant cell, tissue and organ culture 37 (1994), S. 39-46 
    ISSN: 1573-5044
    Keywords: endosperm cell culture ; maize ; protoplast ; transformation ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts were isolated from Zea mays (L.) A69Y endosperm suspension cultures and transformed by polyethylene glycol mediated DNA uptake with chimaeric gene constructs containing β-glucuronidase (GUS) or neomycin phosphotransferase II (NPTII); GUS-expressing and Kanamycin-resistant cultures were recovered. The transformed cells showed integration of the introduced foreign genes into genomic DNA and maintained their ability to synthesize endosperm-specific reserve proteins (zeins). No deletion or rearrangement of zein genes were observed in transformed cultures. Stable transformation of cultured maize endosperm cells may therefore represent a new methodological approach for the study of the transcriptional regulation of endosperm-expressed genes.
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  • 59
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; high performance liquid chromatography ; HPLC ; nutrition ; wheat breeding ; lysine content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An effective method for estimating lysine in wheat gliadin proteins could contribute to increasing lysine in wheat. Wheat gliadin proteins were separated and collected by reverse phase high performance liquid chromatography (RP-HPLC). A fluorimetric assay with o-phthalaldehyde (OPA) was used to determine the lysine content of wheat gliadin proteins. The OPA reagent reacts specifically with the amino group of lysine in protein. Twenty fractions of wheat gliadins were collected and analyzed by the fluorimetric assay. Nine of these fractions were also analyzed for lysine content by an amino acid analyzer. The results obtained from the fluorimetric assay were significantly related to the results obtained from the amino acid analyzer (R=0.93 for quadratic regression of the nine selected gliadin fractions). Lysine content of the wheat gliadins varied from 0.6 to 1.4 percent of the protein. This study determined that the fluorimetric assay could accurately estimate lysine in wheat gliadin proteins. Identification of high-lysine gliadin subunits could be implemented into a program of breeding for increased lysine in wheat.
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  • 60
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    Euphytica 76 (1994), S. 169-175 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; combining ability ; in vitro culture ; genotypic and phenotypic correlations ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Combining ability for six in vitro culture traits in wheat were studied in a 8×8 diallel cross (excluding reciprocals). Specific combining ability effects (sca) were significant for all six traits derived from immature embryos on two media protocols, whereas general combining ability (gca) variances were significant only for five of them. Furthermore, based on ratios obtained by comparing the ratio of K2 gca to K2 sca, sca was more important than gca for all six traits. Genetic correlations between shoot formation and other in vitro traits, except callus weight and root formation, were higher in magnitude than the corresponding phenotypic correlations estimates, indicating the importance of genetic effects.
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  • 61
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    Euphytica 76 (1994), S. 235-238 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; photosynthesis ; gene action ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2). Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.
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  • 62
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    Euphytica 77 (1994), S. 277-282 
    ISSN: 1573-5060
    Keywords: Wheat ; frost tolerance ; diallel cross ; monosomics ; Triticum aestivum ; chromosome substitutions ; wild species ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The frost tolerance of winter wheat is one component of winter hardiness. If seedlings are frost resistant, it means that they can survive the frost effect without any considerable damage. To study the genetic control of frost tolerance, an artificial freezing test was used. Frost tolerance is controlled by an additive-dominance system. The results of diallel analyses indicate the importance of both additive and non-additive gene action in the inheritance of this character. The dominant genes act in the direction of lower frost tolerance and the recessive genes in the direction of a higher level of frost tolerance. The results of monosomic and substitution analyses show that at least 10 of the 21 pairs of chromosomes are involved in the control of frost tolerance and winter hardiness. Chromosomes 5A and 5D have been implicated most frequently. The geneFr1 (Frost 1) was located on the long arm of chromosome 5A. Crosses between cultivars, chromosome manipulation and the induction of somaclonal variation may be suitable methods for broadening the gene pool for frost tolerance.
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  • 63
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    Euphytica 79 (1994), S. 13-18 
    ISSN: 1573-5060
    Keywords: Zea mays ; haploid induction ; maternal haploids ; inducer line ZMS ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Presented are the results of a two-year study of haploid maize plants in the field. The haploids were produced with the aid of inducer line ZMS. In total, 604 and 1030 haploids were obtained and studied in the first and second years, respectively. Tassels of haploid plants were found to be almost completley sterile. Fertility of ears was studied by pollinating them with the pollen from diploid inbred lines, the cross resulting in almost all of the haploid ears carrying kernels. On average 27.4 kernels per ear of haploid plant were obtained in the first year of study and 26.3 in the second. These gave rise to normal diploid plants. This property allows genotypes selected at the level of haploid plants to be involved in breeding process. Unusual plants were found among haploids, phenotypically resembling homozygous lines. It was assumed that the plants had resulted from spontaneous chromosome doubling in haploids. The results of comparative studies of progenies of unusual plants and inbred lines derived from the same synthetic population are presented.
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  • 64
    ISSN: 1573-5060
    Keywords: intergeneric gene transfer ; misdivision ; rye ; Secale cereale ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Sr27 translocation in WRT238 was found to consist of chromosome arms 3RS of rye and 3AS of common wheat. An attempt was made to purposely produce compensating translocations having 3RS and a wheat homoeologous group 3L arm. To achieve this, plants, double monosomic for 3R and a wheat homoeologous group 3 chromosome, were irradiated (7.5 Gy gamma rays) or left untreated before being used to pollinate stem rust susceptible testers. Segregation for stem rust resistance was studied to identify F2 families with Sr27-carrying translocated chromosomes, these were confirmed by means of C-banding. Compensating translocations 3RS3AL and 3RS3BL) were obtained readily and at similar frequencies from untreated and irradiated plants (respectively, 7.2% and 9.3%). Both translocation types have impaired transmission and segregate approximately 3: 2 (present: absent) in the F2.
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  • 65
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    Euphytica 80 (1994), S. 119-124 
    ISSN: 1573-5060
    Keywords: coleoptile tiller ; Triticum aestivum ; vigour ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Faster canopy development in temperate cereals can result in more efficient utilization of wate, light and nutrients if these are in limited supply. It can also result in more competitive plants and less use of herbicides. The possible importance of the coleoptile tiller for increasing early vigour in wheat (Triticum aestivum L.) was determined for twelve F4 lines in two experiments. Each F4 line was chosen for variation in the presence and absence of a coleoptile tiller in plants in the previous generation; each F4 line was traced to a single F2 plant from a multiple convergent cross of sixteen parents. Eight plants of each of the F4 lines were grown in a single row in both experiments. Just after the coleoptile tiller appeared, plants within each line were classified into one of two groups; one group contained plants with large coleoptile tillers whereas the other group had either small coleoptile tillers or none at all. Leaf expansion rates were determined non-destructively at regular intervals, and plants were harvested to determine leaf and tiller characteristics when there were about five mainstem leaves. There was substantial variation in the leaf area of the coleoptile tiller both between groups and among lines. In both experiments plants with a large coleoptile tiller had 24–30% more leaf area and dry weight than plants selected with a small or absent coleoptile tiller up to the final harvest. Leaf expansion rates (increase in leaf area per day) were 25 to 35% greater in the large coleoptile tiller selections from the time tillers first appeared to the time of harvest, whereas the relative leaf expansion rate (increase in leaf area per unit of leaf area present per day) of the large selections was significantly greater than the small selections only at the time of appearance of the coleoptile tiller and just after. There was no evidence that the early appearance of a coleoptile tiller was associated with the largest seedlings or that it inhibited the growth of later tillers. It is concluded that selection for the appearance of a large coleoptile tiller should improve the early vigour of temperate cereals.
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  • 66
    ISSN: 1573-5079
    Keywords: photosynthesis ; leaf age ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.
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  • 67
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    Chromosome research 2 (1994), S. 275-279 
    ISSN: 1573-6849
    Keywords: C-banding ; homoeologous pairing ; homoeologous relationships ; pairing genes ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Homoeologous relationships between the arms of wheat group 2 chromosomes were analysed by studying homoeologous pairing in wheat—rye hybrids. Chromosomes 2A and 2D were identified using telocentrics 2AS, 2DS or 2DL. The remaining wheat chromosomes and their arms were identified by C-banding. Wheat chromosomes in the hybrids were derived from plants which were heterozygous(Ph1/ph1b) and monotelocentric for 2AS, 2DS or 2DL. In these plants, chromosome 2B and the telocentric showed regular bivalent pairing. From the results of homoeologous pairing in wheat—rye hybrids, normal homoeologous relationships between 2AS, 2BS and 2DS, as well as between 2AL, 2BL and 2DL, were deduced. There was no evidence that wheat group 2 chromosomes were involved in evolutionary chromosome rearrangements. The existence of a pairing promoter gene on chromosome arm 2DS was supported.
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  • 68
    ISSN: 1573-8248
    Keywords: Insect parasitoid ; parasitic nematode ; stem borer ; maize ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des enquêtes sur le terrain ont été effectuées entre 1990 et 1992 en vue d'étudier les espèces présentes et l'abondance relative des parasites des lépidoptères foreurs des tigesSesamia calamistis Hampson etEldana saccharina Walker dans des champs de maïs du sud-ouest du Nigéria. Parmi les espèces de parasitoïdes découvertes sur les deux foreurs de tiges figuraient les parasitoïdes des larves et pupes,Sturmiopsis parasitica Curran (Diptera: Tachinidae) etBrachymeria feae Masi (Hymenoptera: Chalcididae), ainsi que le parasitoïde des larves,Dolichogenidea polaszeki Walker (Hymenoptera: Braconidae). Des attaques du braconidéCotesia sesamiae (Cameron) ont été observées surS. calamistis. L'hyperparasitoïdeExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) a été observé sur une pupe deS. parasitica. Des nématodes parasites appartenant àMermis sp. et/ouHexamermis sp. ont été observés sur des larves des deux foreurs des tiges. Dans l'ensemble, le parasitisme larvaire était faible avec des valeurs comprises entre 4.2 et 22.8% pourS. calamistis, et 1.2 et 13% pourE. saccharina. Parmi les parasitoïdes observés, l'espèce la plus courante étaitS. parasitica. Des attaques de quatre hyménoptères parasitoïdes des oeufs ont été observées surS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, etTrichrogrammatoidea eldanae Viggiani (Trichogrammatidae). Les oeufs étaient parasités à des valeurs comprises entre 0 et 33%. L'unique parasitoïde des oeufs observé surE. saccharina étaitT. applanatus Bin et Johnson (Scelionidae) qui ne provoquait qu'un parasitisme de 5%.
    Notes: Abstract Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.
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  • 69
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    Entomologia experimentalis et applicata 67 (1993), S. 143-148 
    ISSN: 1570-7458
    Keywords: Nosema marucae ; microsporidium ; production ; biological control ; cereal stem borer ; Chilo partellus ; maize ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study covering 3 years, experiments were carried out in order to determine the feasibility of producing a microsporidian pathogenNosema marucae in the spotted stalkborerChilo partellus. A maximum yield of 4.9×108 spores/larva (equivalent to 3.1×1010 spores/g fresh larval body weight) was obtained in 3rd instar larvae. It is considered that the production is inexpensive and can be readily adapted for small scale pathogen propagation systems in the tropics.
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  • 70
    ISSN: 1570-7458
    Keywords: LepidopteraEphestia kuehniella ; α-amylase ; Triticum aestivum ; endosperm ; α-amylase inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Crude α-amylase preparations from seven Lepidoptera pests were susceptible to inhibition by salt-soluble proteins of bread wheat (Triticum aestivum L.) endosperm. Protein fractions that corresponded to tetrameric, dimeric, and monomeric wheat α-amylase inhibitors, were decreasingly effective against the insect α-amylase activity. To further confirm these results, purified inhibitors were tested against an α-amylase preparation fromEphestia kuehniella (Zeller). This preparation showed decreased activity when increasing amounts of an heterotetrameric inhibitor (reconstituted from its isolated subunits WTAI-CM2, -CM3 and -CM16) were assayed. Activity was only partially inhibited by homodimeric (WDAI-1, synonym 0.53; WDAI-2, synonym 0.19) and monomeric (WMAI-1, synonym 0.28) inhibitors.
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  • 71
    ISSN: 1570-7458
    Keywords: insecta ; Ostrinia nubilalis ; egg distribution ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between second generation European corn borer (Ostrinia nubilalis Hübner) egg mass numbers and subsequent field corn damage, as measured by stalk cavity numbers, was studied in 79 fields in northeastern North Carolina over three years. A mean of 0.028 egg masses per plant (645 egg masses/23400 plants) was found over the course of the study. Significant differences in oviposition rate were detected between fields and years. Ca. 85% of egg masses were deposited in a five leaf zone surrounding the primary ear; of these, 89% were found on the lower four leaves in this zone. Egg masses appeared to be distributed randomly within fields but at low rates of incidence, and oviposition was relatively uniform between sampling areas within individual fields. Under moderate to high oviposition pressure (mean number of egg masses per plant over the duration of the oviposition period 〉ca. 0.02), eggs laid during the early phases of the oviposition period account for more subsequent stalk damage than eggs laid during the later phases of the oviposition period. Variations in second generation egg mass numbers accounted for ca. 70% of variation in stalk cavity numbers.
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  • 72
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
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  • 73
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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  • 74
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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  • 75
    ISSN: 1432-203X
    Keywords: cryopreservation ; Triticum aestivum ; abscisic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spring wheat (Triticum aestivum L.) zygotic embryos were successfully cryopreserved, without the addition of exogenous cryoprotectants, using only an abscisic acid (ABA) pretreatment. Optimum survival was obtained when embryos were cultured in vitro for 10 days on semisolid Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L (±) ABA prior to cryopreservation. The embryos resumed growth within three days when returned to MS medium devoid of ABA but containing 2mg/L 2,4-dichlorophenoxyacetic acid. The embryogenic calli produced from these embryos exhibited normal plant regeneration on auxin-free media. Changes in dw/fw ratio, as well as the esterified fatty acid and sucrose concentrations correlated positively with the development of tolerance to cryopreservation.
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  • 76
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    Plant cell reports 12 (1993), S. 149-153 
    ISSN: 1432-203X
    Keywords: Triticum aestivum ; microspore culture ; ovary co-culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wheat microspores were isolated, without prior anther culture, from a range of genotypes and cultured to regenerate self-fertile plants. Microspores were isolated using a microblender and competent microspores were enriched by gradient centrifugation. The use of maltose as the sole carbohydrate in the culture medium and co-culture of microspores with wheat or barley ovaries were critical for development of microspore-derived embryos. Results were also improved when spikes were pretreated by emersion of the basal ends of detached heads in water at 25°C for 2d. This procedure leads to highly reproducible production of plants.
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  • 77
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Secale cerele ; Ribosomal RNA genes ; Mitochondrial DNA ; Recombining-repeats ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial genomes of wheat and rye each contain a three-member family of recombining repeat peat sequences (the “18S/5S repeat”) that encode genes for 18S and 5S rRNAs (rrn18 and rrn5) and tRNAfMet (trnfM). Here we present, for wheat and rye, the sequence and boundaries of the “common sequence unit” (CSU) that is shared between all three repeat copies in each species. The wheat CSU is 4,429 base-pairs long and contains (in addition to trnfM, rrn18 and rrn5) a putative promoter, three tRNA-like elements (“t-elements”), and part of a pseudogene (“ψatpA c”) that is homologous to chloroplast atpA, which encodes the α subunit of chloroplast F1 ATPase. The rye CSU is somewhat smaller (2,855 base pairs) but contains much the same genic and other sequence elements as its wheat counterpart, except that two of the three t-elements as well as ψatpA c are found in only one of the three downstream flanks of the 18S/5S repeat, outside the CSU boundaries. In interpreting the seuuence data in terms of the evolutionary history of the 18S/5S-repeat family of wheat and rye, we conclude that (1) the wheat-rye form of the 18S/5S repeat most likely originated between 3 and 14 million years ago, in a lineage that gave rise to wheat and rye but not to barley, oasts, rice or maize; (2) the close linkage (1-bp apart) between trnfM and rrn18 is similarly limited in its taxonomic distribution to the wheat/rye lineage; (3) the trnfM-rrn18 pair arose via a single mutation that inserted a sequence block containing trnfM immediately upstream of rrn18; and (4) the presence of a putative promoter upstream of rrn18 in all wheat and rye repeats is consistent with all three repeat copies being transcriptionally active. We discuss these conclusions in the light of the possible functional significance of recombining-repeats in plant mitochondrial genomes.
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    Plant molecular biology 21 (1993), S. 919-921 
    ISSN: 1573-5028
    Keywords: ARS-related element ; dispersed repeat ; genomic DNA sequence ; molecular evolution ; Secale cereale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A Hind III-generated fragment of wheat embryo nuclear DNA has been cloned and sequenced. The cloned fragment corresponds to a 1241 bp long, moderately repeated (60 000 copies/genome) segment of the genomic DNA. The repeat is AT-rich (67%), contains an open reading frame for 151 amino acids and several nucleotide blocks resembling the consensus domain of autonomously replicating sequences. Southern blot hybridization analyses indicate that the repeat is scattered through the wheat genome. A sequence homologous to this repeat occurs also in rye embryo nuclear DNA where it shows the same dispersion pattern as that observed for the wheat repeat.
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  • 79
    ISSN: 1573-5028
    Keywords: transposable element ; Activator ; gene dosage ; maize ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of Ac copy number on the frequency and timing of germinal transposition in tobacco was investigated using the streptomycin phosphotransferase gene (SPT) as an excision marker. The activity of one and two copies of the element was compared by selecting heterozygous and homozygous progeny of transformants carrying single SPT::Ac inserts. It was observed that increasing gene copy not only increases the transposition frequency, but also occasionally alters the timing of transposition such that earlier events are obtained. The result is that some homozygous plants generate multiple streptomycin resistant progeny carrying the same transposed Ac (trAc) element. We have also investigated the effect of modification of the sequence in the region around 82 bp downstream of the polyadenylation site and 177 bp from the 3′ end of the element on germinal excision frequencies. Alteration of three bases to create a BglII site at this location caused a minor decrease in germinal excision events, but insertion of four bases to create a Cla I site caused a 10-fold decrease in the transposition activity of the Ac element.
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  • 80
    ISSN: 1573-5028
    Keywords: ABA-responsive element ; maize ; tissue-specific factors ; rab genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The maize gene rab28 has been identified as ABA-inducible in embryos and vegetative tissues. It is also induced by water stress in young leaves. The proximal promoter region contains the conserved cis-acting element CCACGTGG (ABRE) reported for ABA induction in other plant genes. Transient expression assays in rice protoplasts indicate that a 134 bp fragment (-194 to -60 containing the ABRE) fused to a truncated cauliflower mosaic virus promoter (35S) is sufficient to confer ABA-responsiveness upon the GUS reporter gene. Gel retardation experiments indicate that nuclear proteins from tissues in which the rab28 gene is expressed can interact specifically with this 134 bp DNA fragment. Nuclear protein extracts from embryo and water-stressed leaves generate specific complexes of different electrophoretic mobility which are stable in the presence of detergent and high salt. However, by DMS footprinting the same guanine-specific contacts with the ABRE in both the embryo and leaf binding activities were detected. These results indicate that the rab28 promoter sequence CCACGTGG is a functional ABA-responsive element, and suggest that distinct regulatory factors with apparent similar affinity for the ABRE sequence may be involved in the hormone action during embryo development and in vegetative tissues subjected to osmotic stress.
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  • 81
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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  • 82
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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    Biochemical genetics 31 (1993), S. 75-86 
    ISSN: 1573-4927
    Keywords: Triticum aestivum ; Wx protein ; two-dimensional polyacrylamide gel electrophoresis ; Wx locus ; waxy mutant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Nullisomic analysis of waxy (Wx) protein of hexaploid wheat (Triticum aestivum L.) cv. “Chinese Spring” using two-dimensional polyacrylamide gel electrophoresis revealed that threeWx loci,Wx-A1, Wx-B1, andWx-D1, located on chromosome arms 7AS, 4AL, and 7DS, produce three distinct Wx subunit groups, subunit group-A (SGA), SGB, and SGD, respectively. SGA has a higher molecular weight and a more basic isoelectric point (pI) than the other two. SGB and SGD have the same molecular weight but a slightly different pI range. Owing to the detection of these three subunit groups, we were able to identify the expression of three waxy genes in wheat endosperm and to find two types of mutants among Japanese wheat cultivars, one lacking SGA and the others SGB. These results suggest the possibility of breeding a waxy wheat.
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  • 84
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    Plant molecular biology 21 (1993), S. 885-893 
    ISSN: 1573-5028
    Keywords: cell wall ; deglycosylation ; extensin ; hydroxyproline-rich ; immunoprecipitation ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the molecular basis for the protein size heterogeneity of extensin from two maize (Zea mays L.) varieties. We studied the physical properties of extensin, a hydroxyproline-rich glycoprotein (HRGP), from the silk and pericarp of Golden X Bantam (GXB) sweet corn and Japanese Hulless (JHL) popcorn. Extensin from GXB has a molecular mass of 66 kDa whereas extensins from JHL have molecular masses of 76 and 66 kDa. Treatment with anhydrous hydrogen fluoride to deglycosylate proteins reduced the size of all extensins by 5 kDa. Probing with a 500 bp fragment from a genomic clone of maize extensin identified two transcripts (1.9 and 1.5 kb) on northern blots. JHL contained both transcripts and GXB contained only the 1.5 kb transcript. The probe also hybridized to two larger transcripts (6.2 and 4.5 kb) that were found in both varieties. We immunoprecipitated two proteins (66 and 56 kDa) from translated RNA isolated from JHL and one protein (56 kDa) from GXB. These results demonstrate that these extensins differ in the size of their peptide moiety and not in their extent of glycosylation.
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  • 85
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    Plant molecular biology 22 (1993), S. 783-792 
    ISSN: 1573-5028
    Keywords: proteinase inhibitor ; wound induction ; wound-induced gene ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have cloned and sequenced a wound-inducible cDNA clone designated WIP1 (for wound-induced protein) from maize coleoptiles. It was isolated by differential screening of a cDNA library prepared from excised maize coleoptile segments. The deduced amino acid sequence predicts a secretory, cysteine-rich protein of 102 residues with a calculated molecular mass of 11 kDa and a typical N-terminal signal sequence. The protein has about 30% identity with various Bowman-Birk type proteinase inhibitors. Most interestingly, it is novel in that it is double-headed with exclusive specificity for chymotrypsin. WIP1 is strongly wound-induced in contrast to other members of the Bowman-Birk proteinase inhibitor family, which occur in seeds and are regulated during development. The response is fast, similar to defenceinduced genes, and measurable as early as 30 min after wounding. Induction can also be evoked in the intact coleoptiles and the signal is systemically transmitted in the coleoptile to adjacent regions of the wounded area. Isolation and analysis of the corresponding genomic clone reveals that WIP1 contains an intron of 90 nucleotides.
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  • 86
    ISSN: 1573-5028
    Keywords: wheat ; Triticum aestivum ; cDNA clone ; ADP-glucose pyrophosphorylase ; small-subunit ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length cDNA clone from hexaploid bread wheat, encoding the small subunit of ADP-glucose pyrophosphorylase, has been isolated from an endosperm cDNA library. The cDNA insert has an open reading frame which encodes a protein of 473 amino acids (52.1 kDa). The presence of a chloroplast/amyloplast transit peptide of 22 amino acids is proposed. The deduced amino acid sequence exhibits a high degree of homology with the small subunit ADP-glucose pyrophosphorylase proteins from rice (with 90% of identical amino acids) and potato (with 86% of identical amino acids) and contains conserved sequence elements which are thought to represent the substrate binding and allosteric activator sites. The genes are organised as single-copy loci on chromosomes 7A, 7B and 7D in the wheat genome and are highly expressed during grain development. Homologous transcripts are expressed in leaves and roots.
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  • 87
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    Plant molecular biology 21 (1993), S. 805-821 
    ISSN: 1573-5028
    Keywords: DNaseI sensitivity ; maize ; methylation ; nucleolar dominance ; rDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Eco RI polymorphism, present in the 26S ribosomal RNA gene (rDNA) of the maize hybrid Sx19 (B73×Mo17), was utilized to correlate DNaseI sensitivity, undermethylation and expression in rDNA. We had previously shown that in double digest experiments with methylation-sensitive restriction enzymes and Eco RI, Sx19 rDNA fragments originating from repeat units with two Eco RI sites (8.0 kb) are undermethylated, whereas the fragments originating from repeat units with a single Eco RI site (9.1 kb) are completely methylated. In the present study, Sx19 rDNA chromatin structure was examined by purifying intact nuclei and digesting them briefly with increasing amounts of DNaseI. Analysis of this DNA with Eco RI showed that the 8.0 kb rDNA fragments are extremely sensitive to DNaseI digestion, while the 9.1 kb rDNA fragments are relatively resistant to digestion even at high levels of DNasel. Specific sites hypersensitive to DNaseI cleavage were mapped to a region in the intergenic spacer (IGS) near the major undermethylated site. Analysis of polymerase chain reaction (PCR) products synthesized using Sx19, B73, and Mo17 DNAs as templates indicated that the Eco RI polymorphism is due to a base change in the recognition site. Direct rRNA sequencing identified a single-base change in Mo17 rRNA relative to B73 rRNA. Allele-specific oligonucleotide probes containing the region surrounding and including the Eco RI polymorphic site were utilized to detect a nucleolar dominance effect by quantitating levels of rRNA transcripts in Sx19 and the reciprocal cross. Results from these single-base-pair mismatch hybridization experiments indicate that the majority of the rRNA transcripts in Sx19 orginate from the DNaseI-sensitive, undermethylated, Eco RI-polymorphic rDNA repeat units.
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  • 88
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    Plant molecular biology 22 (1993), S. 323-336 
    ISSN: 1573-5028
    Keywords: gene cluster ; maize ; multigene family ; transcriptional regulation ; zein ; early in-frame stop codon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cluster of five α-zein subfamily 4 (α-zein SF4) genes are present in a 56 kb region of the maize W22 genome. Two types of α-zein SF4 genes are in the cluster. One of the genes, termed a type 1 (T1) α-zein SF4 gene, contains no early in-frame stop codons. Four of the genes, termed type 2 (T2) α-zein SF4 genes, contain one or two early in-frame stop codons. The base sequence of the T1 α-zein SF4 gene is similar (〉90%) to the sequences of any of the four T2 α-zein SF4 genes. However, their sequences differ markedly at distances greater than -875 bp upstream from the translation initiation codon of the α-zein coding region. This region of dissimilarity is well inside the functional 5′-flanking region for the genes since a 1.8 kb transcript is initiated in this region and the sequences of the T2 α-zein SF4 genes are similar in this region. Two sizes of mRNA transcripts, 1.8 kb and 0.9 kb, were detected in a gene specific manner for 4 of the 5 genes in this α-zein SF4 gene cluster. One of the T2 α-zein SF4 genes had only the 0.9 kb transcript. The RNA level for the 0.9 kb transcript of the T1 α-zein SF4 gene was 5- to 10-fold higher than the transcript levels of any of the T2 α-zein SF4 genes. In each case, the amount of the 0.9 kb transcript detected was at least 5-fold higher than the amount of the 1.8 kb transcript. A cDNA clone with a sequence identical to a T2 α-zein SF4 gene was isolated, providing the first direct evidence for the transcription of T2 α-zein genes containing early in-frame stop codon(s) in maize endosperm.
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  • 89
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    Plant molecular biology 22 (1993), S. 1031-1038 
    ISSN: 1573-5028
    Keywords: maize ; catalase ; genomic clone ; sequence ; gene structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A maize genomic DNA library (Zea mays L. W64A) was constructed using the lambda GEM-11 vector. A gene-specificCat3 cDNA probe was used to screen the library by plaque hybridization. Two independent clones, λ24C and gl27C, which hybridized to theCat3 cDNA probe, were isolated. Restriction maps were created for the two clones (λ24C and λ27C) encoding the maizeCat3 catalase gene. ASal I restriction fragment from each clone was subcloned into pBluescript KS+. Subsequent subcloning steps were performed to obtain plasmids suitable for sequencing. Both strands of the λ24C clone were sequenced. Computer analysis of the putativeCat3 promoter region has not revealed any known transcription factor binding motifs. Analysis of the deduced C-terminal amino acids encoded byCat3 shows that CAT-3 lacks the SRL peroxisomal targeting sequence contained in the CAT-1 and CAT-2 isozymes. The DNA sequence and physical structure of theCat3 gene presented here will be used in characterizingcis- andtrans-acting factors affectingCat3 gene expression.
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  • 90
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    Plant molecular biology 22 (1993), S. 1135-1143 
    ISSN: 1573-5028
    Keywords: maize ; Adh1 gene ; nuclear matrix ; MAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nuclear matrices were isolated from maize leaves by the two conventional methods usually employed for the preparation of the corresponding structures of animal origin. It is demonstrated that functionally competent matrices, recognizing and specifically binding the MAR-containing DNA of the mousek-immunoglobulin gene may be prepared by both 2 M NaCl and LIS extractions of maize nuclei. A DNA region with a high affinity for the nuclear matrix was identified at the 5′ end of the maizeAdh1-S gene, distal to the promoter region. The presence of sites of reported altered chromatin structure in this particular region is discussed. While the proximity and the cohabitation of MARs with different regulatory elements is a common feature of matrix association regions in animal systems, this is the first plant MAR identified in a region of known significance for gene regulation.
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  • 91
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    Plant molecular biology 23 (1993), S. 685-695 
    ISSN: 1573-5028
    Keywords: extensin ; gene expression ; hydroxyproline ; maize ; silk ; vegetative tissues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the developmental regulation of wall-localized, hydroxyproline-containing proteins in maize tissues and organs. Silk and pericarp cell walls contained more peptidyl hydroxyproline than did walls of any vegetative tissue, although all tissues and organs accumulated these proteins as they matured. In many tissues, hydroxyproline-rich proteins are first associated with the wall in a soluble form before being insolubilized through covalent attachment to the matrix. Because hydroxyproline was more soluble earlier than later in development, it appears that insolubilization was occurring in maize tissues and organs as well. Tissue prints reacted with an anti-extensin antibody gave positive results, indicating the presence of a soluble form of this common hydroxyproline-rich glycoprotein (HRGP). Silk and pericarp cells actively synthesized this extensin from abundant transcripts. In vegetative tissues, extensin transcripts were somewhat more abundant in seedlings than in pre-anthesis or mature plants, but levels were much lower than in silk and pericarp. Southern blots of maize genomic DNA indicated that these extensin transcripts are encoded by a small multigene family. Potential roles for extensin in reproductive/protective tissues versus the embryo or vegetative tissues are suggested.
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  • 92
    ISSN: 1432-2242
    Keywords: Aegilops ventricosa ; DNA probes ; Introgression lines ; Addition lines ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stable wheat-Aegilops introgression lines with 42 chromosomes (H-93), derived by repeated selfing from a cross (Triticum turgidum x Aegilops ventricosa) x T. aestivum, have been characterized using the following DNA probes and isozyme markers: (1) single or low-copy DNA fragments from Ae. ventricosa; (2) known cDNA probes corresponding to α1-thionin, monomeric α-amylase inhibitor, the CM3 subunit of tetrameric α-amylase inhibitor, and sucrose synthase from wheat; (3) anonymous cDNA probes from wheat that have been mapped by Sharp et al. (1989); (4) isozyme markers corresponding to aconitase, shikimate dehydrogenase, adenylate kinase, and endopeptidase. Meiotic metaphases of appropriate hybrids involving selected H-93 lines have been investigated by the Giemsa C-banding technique. The substitution of whole chromosomes [(5A) 5Mv; (4D) 4Mv; (5D) 5Mv; (7D) 7Mv] and chromosomal segments (1Mv; 3Mv; 5Mv; 7Mv) from the Mv genome of Aegilops ventricosa has been demonstrated. The distribution of selected markers among putative wheat-Ae. ventricosa addition lines has also been investigated. The 7Mv addition has been characterized for the first time, while the identity of the previously reported 5Mv and 6Mv additions has been confirmed.
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  • 93
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; T. durum ; Aegilops longissimum ; Dasypyrum villosum ; Endonuclease ; Cytoplasm donor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To elucidate the phylogenetic relationships and cytoplasmic types, restriction endonuclease fragment patterns of chloroplast (cp) and mitochondrial (mt) DNAs isolated from two different accessions of Dasypyrum villosum (L.) candargy were compared with those of tetraploid wheat (Triticum durum Desf., PI265007), hexaploid wheat (Triticum aestivum L., cv Chinese Spring), Aegilops longissimum (S. and M., in Muschli) Bowden and Hordeum vulgare L. T. aestivum and T. durum had identical restriction patterns for their cp and mtDNAs in digestions with four different enzymes. Likewise, no differences were found between the restriction fragment patterns of two accessions of D. villosum. But, there were distinct differences in chloroplast and mitochondrial DNA restriction fragment patterns between D. villosum and tetraploid and hexaploid wheats. A. longissimum (G609) showed a similar pattern to those wheats for PstI digestion of cpDNA. Organellar DNA from Hordeum vulgare (cv Himalaya) showed a distinctly different restriction pattern from those of wheat and D. villosum. These results suggest that D. villosum is unlikely to be the donor of cytoplasm to wheats, and its cytoplasmic organelles were also different from those of A. longissimum.
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  • 94
    ISSN: 1432-2242
    Keywords: Grain softness ; Friabilin ; Milling quality ; Triticum aestivum ; Seed storage-proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Mr 15000 protein associated with water-washed wheat starch granules from soft wheats was shown to be heterogeneous: it could be divided into a fraction containing one or moreα-amylase inhibitor subunits and a fraction largely composed of a previously uncharacterised polypeptide(s) referred to as the “grainsoftness protein” (GSP). The major N-terminal sequence and sequences of peptides derived from protease digests of GSP are reported. An antiserum specific for GSP was used to show that GSP accumulated in both hard and soft wheat grains, but the GSP in soft grains associated more strongly with starch granules than the GSP in hard grains. A positive correlation between grain softness and accumulation of GSP in the seed was demonstrated for a range of cultivars. This differs from the qualitative relationship, based on the isolated starch fraction, between GSP and grain softness that has already been reported. Analysis of wholemeal extracts with the antiserum demonstrated that the accumulation of GSP in the seed was dependent on the short arm of chromosome 5D, which also encodes theHa locus. In addition, examination of near-isogenic lines differing in hardness indicated that the gene(s) controlling GSP was (were) linked with theHa locus. The findings indicate that GSP may be the product of theHa locus and thus be the major factor that determines the milling characteristics of bread wheats.
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  • 95
    ISSN: 1432-2242
    Keywords: Rye translocations ; Triticum aestivum ; Glutenin ; Gliadin ; Glu-3 loci ; Gli-1 loci
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A triple (1AL.1RS/1BL.1RS/1DL.1RS) and three double (1AL.1RS/1BL.1RS, 1AL.1RS/1DL.1RS, 1BL.1RS/1DL.1RS) wheat-rye 1RS translocation stocks were isolated from a segregating population using the Gli-1, Tri-1 and Sec-1 seed proteins as genetic markers. These stocks carried 42 chromosomes and formed the expected multivalents (frequency of 14–25%) at metaphase 1. They gave floret fertility ranging from 40–60%. These stocks were subsequently used to determine the genetic control of low-molecular-weight (LMW) glutenin subunits in ‘Chinese Spring’ and ‘Gabo’ by means of two-step one-dimensional SDS-PAGE. All of the B subunits and most of the C subunits of glutenin were shown to be controlled by genes on the short arms of group-1 chromosomes in these wheats. The other C subunits were not controlled by group-1 chromosomes. The triple translocation line served as a suitable third parent in producing test-cross seeds for studying the inheritance of the LMW glutenin subunits and gliadins in wheat cultivars, e.g. ‘Chinese Spring’ and ‘Orca’. The segregation patterns of the LMW glutenin subunits in these cultivars revealed that the subunits were inherited in clusters and that their controlling genes (Glu-3) were tightly linked with those controlling gliadins (Gli-1). The LMW glutenin patterns d, d and e in ‘Orca’ segregated as alternatives to the patterns a, a and a in ‘Chinese Spring’ controlled by Glu-A3, Glu-B3 and Glu-D3 loci on chromosome arms 1AS, 1BS and 1DS, respectively, thus indicating that these patterns were controlled by allelic genes at these loci.
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  • 96
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Thinopyrum bessarabicum ; Protein-isozyme markers ; Chromosome banding ; Intergeneric hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thinopyrum bessarabicum (2n = 2x = 14, JJ) with its unique property of salt tolerance provides a potential means for the transfer of this important and complex trait into cultivated wheat through intergeneric hybridization. To accomplish this, diagnostic markers for detecting the presence of Th. bessarabicum chromosomes in a wheat background have to be established. The C-banded karyotype of Th. bessarabicum distinctly identifies individual Th. bessarabicum chromosomes and separates them from those of Triticum aestivum. Also, seven protein/isozymes, i.e., malate dehydrogenase, high-molecular-weight glutenin, Superoxide dismutase, grain esterase, glutamate oxaloacetate transaminase, β-amylase and α-amylase, were identified as being positive markers specific to Th. bessarabicum; these were also expressed in the T. aestivum/Th. bessarabicum amphiploid. These diagnostic biochemical markers could be useful in detecting and establishing homoeology of Th. bessarabicum chromosomes in T. aestivum/Th. bessarabicum intergeneric hybrid derivatives.
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  • 97
    ISSN: 1432-2242
    Keywords: Gliadin loci ; Group 1 chromosomes ; Recombination ; Electrophoresis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The inheritance and biochemical properties of gliadins controlled by the group 1 chromosomes of the high-quality bread wheat cultivar Neepawa were studied in the progeny of the cross Neepawa x Costantino by six different electrophoretic procedures. Chromosome 1B of Neepawa contains two gliadin loci, one (Gli-B1) coding for at least six ω- or γ-gliadins, the other (Gli-B3) controlling the synthesis of gliadin N6 only. The map distance between these loci was calculated as 22.1 cM. Amongst the chromosome 1A gliadins, three proteins are encoded at the Gli-A1 locus whereas polypeptides N14-N15-N16 are controlled by a remote locus which recombines with Gli-A1. Six other gliadins are controlled by a gene cluster at Gli-D1 on chromosome 1D. Canadian wheat cultivars sharing the Gli-B1 allele of Neepawa were found to differ in the presence or absence of gliadin N6. The electrophoretic mobilities of proteins N6 and N14-N15-N16 were unaffected by the addition of a reducing agent during two-dimensional sodium dodecyl sulphate polyacrylamid-gel electrophoresis, suggesting the absence of intra-chain disulphide bonds in their structure.
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  • 98
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Mildew resistance ; Pm3 locus ; Near-isogenic lines ; RFLP marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to identify molecular markers linked to genes for resistance to powdery mildew (Pm) in wheat using a series of ‘Chancellor’ near-isogenic-lines (NILs), each having one powdery mildew resistance gene. A total of 210 probes were screened for their ability to detect polymorphism between the NILs and the recurrent parent. One of these restriction fragment length polymorphism (RFLP) markers (Xwhs179) revealed polymorphism not only between the NILs for the Pm3 locus, but also among NILs possessing different alleles of the Pm3 locus. The location of the marker Xwhs179 was confirmed to be on homoeologous chromosome group 1 with the help of nullitetrasomic wheat lines. The linkage relationship between this probe and the Pm3 locus was estimated with double haploid lines derived from a cross between wheat cvs ‘Club’ and ‘Chul’ (Pm3b). The genetic distance was determined to be 3.3±1.9 cM.
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  • 99
    ISSN: 1573-9368
    Keywords: Agrobacterium tumefaciens ; maize ; GUS ; gusA/intron ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To develop a system forAgrobacterium-mediated transformation of maize (Zea mays L.), we have investigated histochemically the transient expression of β-glucuronidase (GUS) activity in maize seedling tissue segments using binary vectors that allow minimal (pKIWI105 and pCNL1) or undetectable (p35S-GUS-INT and pCNL56) levels of GUS activity inA. tumefaciens. Tissue segments from three- to five-day-old sterile seedlings of maize genotype A188 were inoculated withA. tumefaciens. Four days after inoculation, transient expression of GUS activity was found in mesocotyl segments originating from the intercalary meristem region. This GUS activity was specific to the vascular cylinder and was not found in the internal cortical or epidermal layers, nor was it found in mature mesocotyl tissue (segments 5 mm below the coleoptilar node). Transient GUS activity was also detected in leaf and coleoptile tissues of shoot segments, but not in the shoot apexper se or in leaves younger than the first leaf. Maize tissues inoculated withA. tumefaciens strains that harbourgusA-containing binary vectors but no Ti-plasmid did not show GUS activity, supporting evidence from previous work thatvir gene activity was essential for the observed GUS activity.A. tumefaciens strains containing different types of Ti-plasmids were also tested. A strain harbouring an agropine-type Ti-plasmid was the most effective for expressing GUS activity in mesocotyl segments, whereas a strain harboring a nopaline-type Ti-plasmid was most effective for expression of GUS activity in the apical meristem-containing segment. These results indicate that different interactions occurred between the differentA. tumefaciens strains and the susceptible plant tissues. Maize genotype specificity for GUS activity in mesocotyl tissues was observed; variations in the cocultivation medium had a profound effect on the frequency of expression of GUS activity.
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  • 100
    ISSN: 1615-6102
    Keywords: Triticum aestivum ; Roots ; Companion cells ; Colchicine ; Abnormal sieve elements ; Plastids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Companion cells (CCs) of seminal roots of wheat (Triticum aestivum L.) flank protophloem sieve elements (PSEs) on their inner side. In roots growing in the presence of 2 mM colchicine prospective CCs are induced to differentiate into abnormal sieve elements. The most convincing evidence that they deviate from their programmed developmental sequence is the deposition of dense crystalloid inclusions within their plastids, a feature characterizing sieve elements of gramineous species. These plastids, however, are ultrastructurally different from those of normal and abnormal PSEs in that they contain only one kind of crystalloid inclusion, exceptionally dense stroma, swollen vesicular structures and plastoglobuli. Mitochondria accumulate in large groups and appear unusually swollen and deformed. Walls develop abnormal thickenings which are deposited irrespective of the position of plasmodesmata. Nuclei become polyploid and appear highly lobed, but degenerate similarly to those in normal sieve elements. Aggregates of paracrystalline material occur in the cytoplasm between the nucleus and cell wall. The end walls display features characterizing developing sieve plates, callose is deposited around plasmodesmata, but sieve pores are not formed. Aberrant CCs may reach “maturity” and co-exist with colchicine-affected PSEs. Their arrangement may be similar to or differ from that of normal phloem poles. Not all cells in CC files are induced to deviate into abnormal sieve elements, nor does their development occur in sequence. Because developmental changes also occur in polyploid cells, which result from colchicine blocked cell divisions, it is concluded that cell division is not a prerequisite for cell differentiation.
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