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  • Zea mays  (76)
  • Springer  (76)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • 2005-2009
  • 1990-1994  (76)
  • 1980-1984
  • 1955-1959
  • 1992  (43)
  • 1991  (33)
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  • 2005-2009
  • 1990-1994  (76)
  • 1980-1984
  • 1955-1959
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 117 (1992), S. 157-161 
    ISSN: 1573-0832
    Keywords: Phyllachora maydis ; Monographella maydis ; Coniothyrium phyllachorae ; Zea mays ; tarspot complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The tarspot complex is caused by the interaction of Phyllachora maydis and Monographella maydis. Coniothyrium phyllachorae, possibly a mycoparasite, is found in older ascostromata of P. maydis, which always appears first causing tarspot. M. maydis follows and is responsible for the damaging “fisheye” symptom. The fisheye symptom is always associated with a tarspot in the center of the lesion, whereas 12 to 20% of the Phyllachora ascostromata remained free of M. maydis. Inoculations of maize leaves with the Microdochium anamorph of the Monographella (usually produced in lesions) failed to produce infections. Some infections with M. maydis were, however, obtained under unusual conditions in the field. Inoculations onto tarspots in the laboratory were unsuccessful, but in field experiments inoculations with conidia of M. maydis enhanced severity of the tarspot complex. Fisheye symptoms of the complex naturally appear 2 to 7 days after the manifestation of P. maydis. This is followed a week later by the appearance of M. maydis which became predominant in the lesions and is associated with empty perithecia of P. maydis. In the early stages of the tarspots pycnidia of the anamorph of P. maydis, Linochora sp., could occasionally be observed. Ascomata of M. maydis were rare in the field. Of the 36 genetic materials of CIMMYT tested, 30 developed the fisheye symptom, 4 tarspots only and 2 remained free of symptoms
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  • 2
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    Mycopathologia 119 (1992), S. 181-190 
    ISSN: 1573-0832
    Keywords: aflatoxin B1 ; electron microscopy ; in vitro ; immature maize embryo ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immature maize (Zea mays L.) embryos were treated with aflatoxin B1 concentrations, ranging from 0.1 μg ml−1 to 25 μg ml−1. Below 5 μg ml−1 aflatoxin B1, root and shoot elongation was not significantly inhibited. Ultrastructurally, root tip cells showed little deterioration, except a possible diffused clearing in mitochondria and plastids. As the toxin concentration was increased above 5 μgml−1, shoot, and particularly root elongation, was progressively inhibited. Associated with this, there was an apparent decrease in the ribosome population. Furthermore, membranes, particularly the vacuolar membrane, became abnormal and vacuolar distension occurred. At 20 and 25 μg ml−1, these effects were exacerbated, and mitochondria and plastid structure was disrupted. At these concentrations, there was evidence of a disruption in lipid metabolism. The results are discussed in the context of known aflatoxin effects on cellular control mechanisms and ultrastructure in animal systems.
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  • 3
    ISSN: 1432-2048
    Keywords: Ammonium compartmentation ; Cytoplasm ; Vacuole ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We show that the pH dependence of the base-catalysed exchange rate of the ammonium ion provides a basis for discriminating between the cytoplasmic and vacuolar pools of ammonium in plant tissues. In vivo, 14N-nuclear magnetic resonance spectra were recorded with and without 1H-decoupling and information on the subcellular distribution of NH 4 + was obtained from a lineshape analysis of the 1H-coupled spectrum. We applied this method to maize (Zea mays L.) root tissues and found that: (i), the cytoplasmic ammonium concentration was low, which was in accord with the large activity of glutamine synthetase present in the roots; and (ii), inhibition of glutamine synthetase with methionine sulphoximine increased the cytoplasmic ammonium concentration, and led to the appearance of ammonium in the xylem sap.
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  • 4
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    Plant cell reports 11 (1992), S. 567-570 
    ISSN: 1432-203X
    Keywords: Microspore ; Electroporation ; Transformation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability to deliver and detect reporter gene activity in maize microspores was tested. Tested expression vectors contained the chloramphenicol acetyl transferase (CAT) gene and one of the following promoter-intron combinations: 1) cauliflower mosaic virus (CaMV 35S), 2) CaMV 35S + maize alcohol dehydrogenase 1 intron 6 (Adh1-I6), 3) maize alcohol dehydrogenase 1 + intron 1 (Adh1-I1), or 4) maize ubiquitin 1 + intron 1 (Ubiq 1-I1) promoter + intron. The expression vectors were delivered into maize microspores using electroporation or polyethylene glycol (PEG). Both methods were effective for delivering free DNA into microspores. Although all four promoters were active in maize protoplasts, only two promoters were active in maize microspores. The CaMV 35S and the Adh1 promoters did not promote gene expression in maize microspore. The CaMV 35S + Adh1-I6 and Ubiq1-I1 promoters produced high levels of CAT activity in maize microspores.
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  • 5
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    Sexual plant reproduction 5 (1992), S. 224-226 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Polyembryony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two types of cleavage polyembryony are described in the inbred line VIR 17 of maize. Suspensorial embryony was observed to occur spontaneously. Typical cleavage of the zygotic proembryo occurred spontaneously, but could also be induced by treating the developing caryopses with 2,4-Dichlorophenoxyacetic acid (2,4-D) on the second day after pollination. 2,4-D was active as a decorelative factor also evoking the expression of totipotency in individual proembryonal cells.
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  • 6
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    Sexual plant reproduction 4 (1991), S. 12-16 
    ISSN: 1432-2145
    Keywords: In vitro fertilization ; Egg cell ; Sperm cell ; Electrofusion ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electrofusion-mediated in vitro fertilization of maize using single sperm and egg cells was performed. Sperm cells were released from pollen grains after rupture of the latter by osmotic shock in the fusion medium (0.55 M mannitol). Egg cells were isolated by enzyme treatment (pectinase, pectolyase, hemicellulase, and cellulase) followed by mechanical isolation. The conditions generally used for the electrical fusion of protoplasts of somatic cells were also applied to the protoplasts of gametic cells of maize. Electrofusion was performed with single pairs of gametes under microscopic observation. The mean fusion frequency was 79%. Isolated egg cells of maize showed protoplasmic streaming during 22 days of culture, but they did not divide. However, after fusion of the sperm with the egg cells, these fused cells did develop, with a mean division frequency of 83%, and grew to multicellular structures. Egg cells and fusion products were cultivated with a maize feeder-cell system.
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  • 7
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    Sexual plant reproduction 5 (1992), S. 227-231 
    ISSN: 1432-2145
    Keywords: Zea mays ; Maize ; Pollen-tube growth regulation ; In vitro pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In vitro pollen-tube growth in maize was studied using an in vitro pollination system. In the ‘cut-silk’ method, ovaries with silks were placed on medium in vitro, whereafter the silk was cut and the upper part of the silk was pollinated. Pollen tubes were not able to bridge the space between the two silk parts. Even when silk parts were tightly connected, pollen tubes still were not able to pass the cut ends and reach the lower silk part. Pollen-tube growth rates and the direction of tube growth were not influenced by the presence or absence of an ovary. Prepollination did not have any influence on pollen-tube growth rate. Measurements of pollen-tube growth rate also showed that there was no ‘population effect’, i.e. growth rate was not stimulated by pollination with an excess of pollen grains. We found that the direction in which maize pollen grew was determined only by the positioning of the silk hairs.
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  • 8
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    Plant cell reports 11 (1992), S. 535-539 
    ISSN: 1432-203X
    Keywords: Zea mays ; in vitro culture ; in vitro pollen ; pollen germination ; fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maturation of maize pollen was obtained in male reproductive structures cultured in vitro. Immature tassels containing microspores at the mid-uninucleate to late-binucleate stage of development were excised and spikelets, anthers, and/or isolated microspores were cultured on a medium capable of supporting pollen maturation. Microspore mitosis, culminating in the production of starch-filled, trinucleate pollen capable of germination, was observed after 7–15 days, depending on the genotype and stage at which the cultures were initiated. Up to 100%, 70%, and 20% of the cultured spikelets, anthers, and isolated microspores, respectively, produced mature pollen, which germinated, however, at different frequencies (i.e., spikelets, 50–70%; anthers, 5–10%; microspores, 〈1%). Mature kernels were produced following fertilization with pollen from cultured spikelets and anthers. These procedures provide methods for the in vitro manipulation of a significant phase of the maize life cycle.
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  • 9
    ISSN: 1432-203X
    Keywords: Zea mays ; Matrix-associated ; DNA ; repetitive sequences ; DNA loops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to elucidate some features of the topological organization of DNA within the plant nucleus, DNA fragments involved in the attachment of the DNA loops to the nuclear matrix in maize were studied. The matrix-associated DNA from dry embryo and meristematic cells after extensive digestion with DNase I and high salt treatment was about 2% of the total DNA, sized within the range of 50 and 250 bp. This DNA was found to be enriched in repetitive DNA sequences, both for nuclei from dry embryo and meristematic cells. The loop size of the DNA in cells of Zea mays appeared to be between 5 and 25 kbp.
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  • 10
    ISSN: 1432-0789
    Keywords: Vigna unguiculata ; Zea mays ; Nutrient competition ; Intercropping ; Nitrate depletion ; N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha-1 year-1 as urea) and P application (0 and 60 kg P ha-1 year-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N2 fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N2 fixation was low, with the highest values in the sole cropping (53 kg ha-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N2 fixation. This was substantiated by nodule counts. The lower N2 fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N2 fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior.
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  • 11
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    Biology and fertility of soils 13 (1992), S. 142-146 
    ISSN: 1432-0789
    Keywords: A value ; Common bean ; N remobilization ; Soil N balance ; Atom% 15N excess ; Phaseolus vulgaris ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The common bean (Phaseolus vulgaris L.) is generally regarded as a poor N2 fixer. This study assessed the sources of N (fertilizer, soil, and fixed N), N partitioning and mobilization, and soil N balance under field conditions in an indeterminate-type climbing bean (P. vulgaris L. cv. Cipro) at the vegetative, early pod-filling, and physiological maturity stages, using the A-value approach. This involved the application of 10 and 100 kg N ha-1 of 15N-labelled ammonium sulphate to the climbing bean and a reference crop, maize (Zea mays L.). At the late pod-filling stage (75 days after planting) the climbing bean had accumulated 119 kg N ha-1, 84% being derived from fixation, 16% from soil, and only 0.2% from the 15N fertilizer. N2 fixation was generally high at all stages of plant growth, but the maximum fixation (74% of the total N2 fixed) occurred during the interval between early (55 days after planting) and late podfilling. The N2 fixed between 55 and 75 days after planting bas a major source (88%) of the N demand of the developing pod, and only about 11% was contributed from the soil. There was essentially no mobilization of N from the shoots or roots for pod development. The cultivation of common bean cultivars that maintain a high N2-fixing capacity especially during pod filling, satisfying almost all the N needs of the developing pod and thus requiring little or no mobilization of N from the shoots for pod development, may lead to a net positive soil N balance.
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  • 12
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    Journal of chemical ecology 18 (1992), S. 1227-1237 
    ISSN: 1573-1561
    Keywords: Western corn rootworm ; Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; bacteria ; carbon dioxide ; pheromone ; semiochemicals ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract FemaleDiabrotica virgifera virgifera LeConte were allowed to choose between oviposition substrates that were and those that were not associated with potential sources of semiochemicals. Females deposited over five times more eggs on moist towelettes that were treated with homogenates of female abdomens than on towelettes treated with distilled water. Similar results were obtained when screening separated the homogenates from the towelettes, indicating that odors alone could elicit the response. In contrast, females did not choose towelettes that had previously been used for oviposition or towelettes containing eggs over unused towelettes. Further tests with homogenates of abdomens and a bacteriostatic agent (sorbate) indicated that the females were probably responding to bacterial odors rather than an oviposition-enhancing pheromone. Four strains of bacteria were isolated from a homogenate of female abdomens; females deposited 4 to 16 times more eggs on substrates with odors of the bacteria than on substrates with odors of uninoculated nutrient agar. In no-choice tests, bacterial odors did not increase the number of eggs deposited per female beetle; however, in choice tests with dishes that tended to retain any beetles that entered, there were more eggs per female (but not more beetles) after 24 hr in dishes with bacterial odors than in those without the odors. Females also chose dishes with odors of excised maize (Zea mays L.) roots or elevated levels of carbon dioxide over “control” dishes.
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  • 13
    ISSN: 1573-5028
    Keywords: geminivirus ; agroinfection ; Zea mays ; large intergenic region (LIR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize streak virus as well as other geminiviruses contain a potential hairpin structure with the conserved sequence TAATATTAC in the loop. We assessed the possible involvement of this structure in replication and symptom induction of the virus. A series of insertion and deletion mutants were analyzed by agroinfection. Deletion of the hairpin or insertions in the conserved sequence abolished symptom development. Viral DNA could not be detected in the infected tissue. However, a mutant with a point mutation in the ‘conserved’ sequence, isolated after inoculation of maize plants with an insertion mutant, was able to replicate and to induce symptoms.
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  • 14
    ISSN: 1573-5028
    Keywords: cortex ; developmental regulation ; in situ hybridization ; organ-specific gene expression ; roots ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A near full-length cDNA clone (pZRP3) corresponding to an mRNA that accumulates specifically in roots of maize was isolated. The ZRP3 mRNA is ca. 600 nucleotides in length. The amino acid sequence of the predicted polypeptide is rich in leucine (16%), proline (11%), and cysteine (8.5%). The zrp3 gene appears to be expressed exclusively in roots, whereas other ZRP3-related genes are expressed in additional organs of the maize plant. In situ hybridization shows that ZRP3 mRNA accumulation is largely confined to the cells of the cortical ground meristem. Furthermore, accumulation of this mRNA occurs within a distinct subset of cortical cells, the inner three to four cell layers.
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  • 15
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    Plant molecular biology 20 (1992), S. 1159-1168 
    ISSN: 1573-5028
    Keywords: DNA polymerase ; germination ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three different DNA polymerase activities can be resolved by passing a protein extract from 24 h imbibed maize axes through DEAE-cellulose. These activities have been numbered 1, 2 and 3, according to their elution order. One of them, DNA polymerase 2, elutes at 100–120 mM phosphates. This enzyme was further purified by passing it through Heparin-Sepharose, Sephacryl S-300 and DNA cellulose. Purification was nearly 5000-fold. The enzyme needs Mg2+, is stimulated by K+, has an optimum pH of 7.0 and its optimum temperature is 30–37 °C. Specific inhibitors for different types of polymerases, such as aphidicolin, dideoxythymidine triphosphate and N-ethyl maleimide, gave intermediate values of inhibition, making impossible the definition of the type of enzyme purified by its inhibitory pattern. SDS-PAGE indicated the presence of several bands of molecular masses of 28–40, 56 and 15 kDa. Most of these bands could be visualized when proteins from crude extracts were analyzed by western blot, using an antibody against calf thymus DNA polymerase α. A high molecular mass (around 500 kDa) was calculated by western blot of native gels using the same antibody. Finally, specific activity of this enzyme increased 100-fold during maize germination whereas polymerase 3 virtually did not increase. Furthermore, immunoprecipitation experiments with the antipolymerase α-antibody showed a decrease in DNA polymerase activity by 70%. The possibility that polymerase 2 is a replicative enzyme is discussed.
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  • 16
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    Plant molecular biology 16 (1991), S. 919-923 
    ISSN: 1573-5028
    Keywords: Zea mays ; maize ; embryogenesis ; abscisic acid ; seed maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated by differential hybridization a cDNA, termed Emb564, which is complementary to an 800 nt embryo-specific transcript in Zea mays. The expression of Emb564 can be enhanced by exogenous abscisic acid (ABA) and the effect of ABA on the accumulation of Emb564 transcript appears to be confined to embryos at the early and mid embryonic stages. In addition, Emb564 is expressed at low levels in ABA-deficient but not in ABA non-responsive embryos. Genomic analysis suggested that the Emb564 mRNA is encoded by a single gene. Sequence analysis showed that Emb564 exhibits extensive similarities with several known ABA-inducible genes.
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  • 17
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    Plant molecular biology 18 (1992), S. 847-849 
    ISSN: 1573-5028
    Keywords: cDNA ; nucleotide sequence ; glycine-rich proteins ; chemical stress ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 18
    ISSN: 1573-5028
    Keywords: promoter ; electroporation ; protoplasts ; transient assay ; Agrobacterium ; Ti plasmid ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regulatory elements controlling transcriptional activity of the mannopine synthase 2′ promoter (mas 2′) were defined by analysis of deletion mutants in transient expression assays in maize protoplasts. Deletion of the region between −305 and −290 containing sequence similarity to the octopine synthase (ocs) promoter element reduced activity by 67% compared to wild type activity. Less than 1% of the activity remained in 5′ deletions downstream of −153. Inclusion of various heterologous enhancer-like sequences immediately upstream of position −325 increased activity by up to 7.5-fold. Insertion of the −325 to −275 sequence alone, or in combination with heterologous enhancer-like elements, restored activity of some of the 5′-deletion mutants. Restoration of activity was not obtained with mutants deleted past position −127. Our results suggest that a single class of nuclear proteins from maize interact with high affinity at elements designated mas b (−306 to −275; mas 1′ element), d (−127 to −108), and e (−82 to −39; mas 2′ element) as well as the 20 bp element from the ocs promoter. Although the binding site at mas d only appears to accommodate a single protein, this element has the potential to make a weak, but positive, contribution to the activity of the mas 2′ promoter. The binding of nuclear proteins could not be demonstrated at mas a and c, both of which showed limited homology to the ocs element. Mutational evidence suggested that mas a and c may also contribute to mas 2′ transcription.
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  • 19
    ISSN: 1573-5028
    Keywords: ribosomal protein ; rps12 ; rpl20 ; clpP ; chloroplast genome ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 20
    ISSN: 1573-5028
    Keywords: cycloheximide ; leaf ; nitrate induction ; nitrate reductase transcript ; root ; scutellum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nitrate induction of NADH:nitrate reductase mRNA in maize roots, scutella and leaves was investigated in the presence and absence of inhibitors of protein synthesis. In the absence of inhibitors, nitrate treatment caused a fairly rapid (2 to 3 h) increase in the level of the nitrate reductase transcript in all tissues. When cytoplasmic protein synthesis was inhibited by cycloheximide, nitrate reductase mRNA was induced by nitrate in all tissues to levels equal to or greater than those found with nitrate treatment alone. Treatment of maize tissues with cycloheximide in the absence of nitrate had only a small effect on the accumulation of the nitrate reductase mRNA. Inhibition of organellar protein synthesis with chloramphenicol also had little or no effect on nitrate-induced nitrate reductase mRNA accumuiation in roots and scutella, but did appear to partially inhibit appearance of transcript in leaves. Excision of scutella in the absence of nitrate was sufficient to cause some accumulation of the nitrate reductase transcript. Since cytoplasmic protein synthesis was not required for expression of nitrate reductase transcripts, induction of these transcripts by nitrate is a primary response of maize to this environmental signal. Thus, it appears that the signal transduction system mediating this response is constitutively expressed in roots, scutella and leaves of maize.
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  • 21
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; ATPase ; cpn60 ; developmental regulation ; molecular chaperones ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria contain a nuclear-encoded heat shock protein, HSP60, which functions as a chaperonin in the post-translational assembly of multimeric proteins encoded by both nuclear and mitochondrial genes. We have isolated and sequenced full-length complementary DNAs coding for this mitochondrial chaperonin in Arabidopsis thaliana and Zea mays. Southern-blot analysis indicates the presence of a single hsp60 gene in the genome of A. thaliana. There is a high degree of homology at the predicted amino acid levels (43 to 60%) between plant HSP60s and their homologues in prokaryotes and other eukaryotes which indicates that these proteins must have similar evolutionarily conserved functions in all organisms. Northern- and western-blot analyses indicate that the expression of the hsp60 gene is developmentally regulated during seed germination. It is also heat-inducible. Developmental regulation of the (β-subunit) of F1-ATPase, an enzyme complex that is involved in the cyanide-sensitive mitochondrial electron transport system, indicates that imbibed embryos undergo rapid mitochondrial biogenesis through the early stages of germination. Based on the functional role of HSP60 in macromolecular assembly, these data collectively suggest that the presence of higher levels of HSP60 is necessary during active mitochondrial biogenesis, when the need for this protein is greatest in assisting the rapid assembly of the oligomeric protein structures.
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  • 22
    ISSN: 1573-5028
    Keywords: pollen-specific gene expression ; promoter analysis ; transient assays ; Tradescantia ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have previously reported the isolation and characterization of a gene (Zm 13) from Zea mays which shows a pollen-specific pattern of expression. Stably transformed tobacco plants containing a reporter gene linked to portions of the Zm 13 5′ flanking region show correct temporal and spatial expression of the gene. Here we present a more detailed analysis of the 5′ regions responsible for expression in pollen by utilizing a transient expression system. Constructs containing the β-glucuronidase (GUS) gene under the control of various sized fragments of the Zm13 5′ flanking region were introduced into Tradescantia and Zea mays pollen via high-velocity microprojectile bombardment, and monitored both visually and with a fluorescence assay. The results suggest that sequences necessary for expression in pollen are present in a region from −100 to −54, while other sequences which amplify that expression reside between −260 and −100. The replacement of the normal terminator with a portion of the Zm13 3′ region containing the putative polyadenylation signal and site also increased GUS expression. While the −260 to −100 region contains sequences similar to other protein-binding domains reported for plants, the −100 to −54 region appears to contain no significant homology to other known promoter fragments which direct pollen-specific expression. The microprojectile bombardment of Tradescantia pollen appears to be a good test system for assaying maize and possibly other monocot promoter constructs for pollen expression.
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  • 23
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    Plant molecular biology 17 (1991), S. 265-268 
    ISSN: 1573-5028
    Keywords: cDNA sequence ; cytoplasmic ribosomes ; gene copy number ; ribosomal protein S11 ; steadystate mRNA level ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We isolated a Zea mays cDNA encoding the 40S subunit cytoplasmic ribosomal protein S11. The nucleotide sequence was determined and the derived amino acid sequence compared to the corresponding Arabidopsis thaliana protein showing an homology of 90%. This ribosomal protein is encoded by a small multigene family of at least two members. The mRNA steady-state level is about one order of magnitude higher in rapidly growing parts of the plant such as the roots and shoots of seedlings compared to fully expanded leaf tissue.
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  • 24
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    The journal of membrane biology 119 (1991), S. 277-288 
    ISSN: 1432-1424
    Keywords: Ca2+-activated K+ current ; Ca2+ channel ; Zea mays ; 1,4-dihydropyridine ; phenylalkylamine ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The voltage- and time-dependent K+ current,I K + out , elicited by depolarization of corn protoplasts, was inhibited by the addition of calcium channel antagonists (nitrendipine, nifedipine, verapamil, methoxyverapamil, bepridil, but not La3+) to the extracellular medium. These results suggested that the influx of external Ca2+ was necessary for K+ current activation. The IC50, concentration of inhibitor that caused 50% reduction of the current, for nitrendipine was 1 μm at a test potential of +60 mV following a 20-min incubation period. In order to test whether intracellular Ca2+ actuated the K+ current, we altered either the Ca2+ buffering capacity or the free Ca2+ concentration of the intracellular medium (pipette filling solution). By these means,I K + out could be varied over a 10-fold range. Increasing the free Ca2+ concentration from 40 to 400nm also shifted the activation of the K+ current toward more negative potentials. Maintaining cytoplasmic Ca2+ at 500nm with 40nm EGTA resulted in a more rapid activation of the K+ current. Thus the normal rate of activation of this current may reflect changes in cytoplasmic Ca2+ on depolarization. Increasing intracellular Ca2+ to 500nm or 1 μm also led to inactivation of the K+ current within a few minutes. It is concluded thatI K + out is regulated by cytosolic Ca2+, which is in turn controlled by Ca2+ influx through dihydropyridine-, and phenylalkylamine-sensitive channels.
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    Theoretical and applied genetics 81 (1991), S. 635-640 
    ISSN: 1432-2242
    Keywords: Catalase null ; Zea mays ; Catalase transcript ; Transposable element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The molecular basis for a shorter Cat2 transcript in maize lines null for the CAT-2 catalase iso/yme was investigated using cDNA libraries and genomic DNA blots. Sequence comparison of partial Cat2 cDNAs obtained from two CAT-2 null lines and a wild-type CAT-2 encoding cDNA showed that the Cat2 null transcripts diverged from the wild-type transcript but remained homologous to each other. Genomic DNA blots indicated that the missing portion of the transcript is present in the genomes of lines null for the CAT-2 isozyme. Differences in the hybridization patterns of normal and null lines were revealed when genomic DNA blots were probed with the full-length Cat2 cDNA, a Cat2 gene-specific probe, and a “null sequence” probe. Together, the DNA blotting results suggest that a rearrangement of the Cat2 gene has occurred in the CAT-2 null lines. The available data suggest that the CAT-2 null mutation in maize is due to a DNA insertion into the Cat2 gene.
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  • 26
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    Theoretical and applied genetics 81 (1991), S. 185-188 
    ISSN: 1432-2242
    Keywords: Zea mays ; Recombination ; A1 locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We find that recombination between two alleles of the maize A1 locus that contain transposon insertions at known molecular positions can occur at 0.04–0.08 cM per kbp (centimorgan per kilobase pair), which is two orders of magnitude higher than the recombination rate for the whole maize genome. It is however, close to the rates found within the bronze locus, another maize structural gene for which both genetic and molecular data are available. This observation supports the idea that the genome consists of regions that are highly recombinogenic — in some cases, at least, structural genes — interspersed with regions that are less recombinogenic.
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  • 27
    ISSN: 1432-2242
    Keywords: Zea mays ; Chromosome doubling ; Amiprophos methyl ; Pronamide ; Oryzalin ; Trifluralin
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    Topics: Biology
    Notes: Summary Four antimicrotubule herbicides, amiprophosmethyl (APM), pronamide, oryzalin, and trifluralin, were evaluated for their ability to induce chromosome doubling in anther-derived, haploid maize callus. Effects of various herbicide treatments on the growth and regenerative capacity of callus along with the ploidy and seed set of regenerated plants were determined. Flow cytometric analysis was also used to measure changes in ploidy levels of callus cells following treatments. More than 50% of the cells were doubled in chromosome number after the haploid callus was treated with 5 or 10 μ M APM or 10 μ M pronamide for 3 days. A similar proportion of plants regenerated from the treated callus produced seed upon self-pollination. APM and pronamide did not inhibit callus growth at these concentrations and the treated callus retained a high plant regeneration capacity. Oryzalin very effectively induced chromosome doubling, but severely inhibited the growth of regenerable callus and plant regeneration. Trifluralin induced chromosome doubling in a small proportion of cells at lower concentrations (0.5 and 1 μ M), however, at a higher concentration (5 μM) it inhibited callus growth and plant regeneration. The results indicate that APM and pronamide may be useful agents for inducing chromosome doubling of anther-derived maize haploid callus at very low concentrations.
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  • 28
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    Theoretical and applied genetics 84 (1992), S. 798-802 
    ISSN: 1432-2242
    Keywords: Zea mays ; C-banding ; Cell size ; Chloroplast number ; Cold tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary C-band number, guard cell length, and chloroplast number per guard cell were determined for eight maize populations. These populations consisted of maize selected for cold tolerance at the University of Nebraska as well as the original unselected populations. The genome size of these populations had previously been determined. C-band number fluctuated concertedly with the changes in genome size indicating that deletions and additions of constitutive heterochromatin occurred during selection, resulting in altered genome sizes. Guard cell size of all the cold tolerant populations was greater than the cell size of the respective nonselected populations. Chloroplast number per guard cell was also higher in all the cold tolerant populations than in their parental populations, but the increases were not statistically significant. The results indicate that changes in genome size that occurred during selection for cold tolerance are the result of changes in amounts of C-band heterochromatin and that the selection process results in an increase in cell size in the cold tolerant populations.
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  • 29
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    Theoretical and applied genetics 81 (1991), S. 162-165 
    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Stability ; Maize ; Zea mays ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genotype x environment (GE) interaction encountered in experiments complicates genotype selection and varietal recommendation. The integration of yield and stability of genotypes into a single parameter may make selection and recommendation easier. Kang developed a rank-sum method that allows selection for both yield and the stability variance statistics (σ i 2 or s i 2 ) of Shukla. The objective of this research was to compare the rank-sum selection method to selection based on yield alone in five international maize (Zea mays L.) yield trials. Ranks were assigned for yield (the highest mean yield received a rank of 1) and for σ i 2 and s i 2 (the lowest value received a rank of 1). The yield and σ i 2 ranks and/or the yield and s i 2 ranks for each genotype were summed. Each trial contained two reference entries (REs). Yield rank or rank-sum of each genotype was compared to yield rank or rank-sum of the best RE (BRE). GE interaction was significant for all trials. Heterogeneity in the GE interaction due to the linear effect of a covariate (differences in fertility and/or cultural practices) was significant in Trials 1, 2, and 5. Overall, in all trials, 29 genotypes were selected on the basis of yield alone. On the basis of σ i 2 and yield rank-sum, 32 genotypes were identified, with 11 being lower yielding than the 29 yield-based selections. On the basis of s i 2 and yield rank-sum, 31 genotypes were selected, with 11 being lower yielding than the yield-bases selections. Obviously, yield is sacrificed when the rank-sum method is used in the selection process. However, selection based on yield alone may not be adequate when GE interaction is significant because of testing in diverse environments.
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  • 30
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    Theoretical and applied genetics 81 (1991), S. 227-232 
    ISSN: 1432-2242
    Keywords: Callus cultures ; RFLP ; Zea mays ; Oryza sativa ; Regeneration ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tissue culture of the Zea mays inbred line A188 resulted in the regeneration of plants having a high level of phenotypic variation compared to seed-grown control plants. To determine how such variation was induced and whether this could be related to specific in vitro culture methods, callus cultures were established and maintained on different, commonly used culture media. Plants were regenerated and the genomic DNA of callus cultures and regenerants analysed for RFLP differences. The results show that regardless of the gene probe used, callus formation resulted in significant deviations from the DNA pattern normally found in seed-grown control plants. Alterations in gene copy number also occurred. As differentiation and organogenesis began, the level of DNA variation fell, and most of the regenerated plants showed a genetic similarity to the controls; those with RFLP differences were the somaclonal variants.
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  • 31
    ISSN: 1432-2242
    Keywords: Zea mays ; Parentage determination ; Varietal identification ; Genetic polymorphisms ; Genetic markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using a novel procedure based on the polymerase chain reaction, we have developed a rapid, efficient, and economical method for identifying plant genotypes. The arbitrarily primed polymerase chain reaction (AP-PCR) generates reproducible fingerprints from any organism, without the need for DNA sequence information. These fingerprints include DNA fragment polymorphisms that can be (1) used for varietal identification and parentage determination, (2) followed in segregating populations produced by crosses, (3) used as markers for the construction of genetic maps, and (4) used to generate dendograms of phylogenetic relationships, especially at the intraspecific level. AP-PCR requires only minute quantities of DNA (10–25 ng per reaction) and therefore can be used in situations in which DNA is limiting. We demonstrate the use of AP-PCR to identify inbred parents of hybrid maize plants in double-blind experiments.
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  • 32
    ISSN: 1432-2242
    Keywords: Zea mays ; Restriction fragment length polymorphisms (RFLPs)-Phosphorus (P) stress-quantitative trait loci (QTLs)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An understanding of the genetic nature underlying tolerance to low-phosphorus (low-P) stress could aid in the efficient development of tolerant plant strains. The objective of this study was to identify the number of loci in a maize (Zea mays L.) population segregating for tolerance to low-P stress, their approximate location, and the magnitude of their effect. Seventy-seven restriction fragment length polymorphisms (RFLPs) were identified and scored in a maize F2 population derived from a cross between line NY821 and line H99. The F2 individuals were self-pollinated to produce F3 families. Ninety F3 families were grown in a sand-alumina system, which simulated diffusion-limited, low-P soil conditions. The F3 families were evaluated for vegetative growth in a controlled-environment experiment. To identify quantitative trait loci (QTLs) underlying tolerance to low-P stress, the mean phenotypic performances of the F3 families were contrasted based on genotypic classification at each of 77 RFLP marker loci. Six RFLP marker loci were significantly associated with performance under low-P stress (P〈0.01). One marker locus accounted for 25% of the total phenotypic variation. Additive gene action was predominant for all of the QTLs identified. Significant marker loci were located on four separate chromosomes representing five unlinked genomic regions. Two marker loci were associated with an additive by additive epistatic interaction. A multiple regression model including three marker loci and the significant epistatic interaction accounted for 46% of the total phenotypic variation. Heterozygosity per se was not predictive of phenotypic performance.
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  • 33
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    Protoplasma 169 (1992), S. 49-56 
    ISSN: 1615-6102
    Keywords: Lectin ; Plasma membrane ; Protoplast isolation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An improved method for the mechanical release of protoplasts from plant tissues is described. The historically-low yield of mechanically-released protoplasts is greatly increased by use of a simple electrically-driven tissue sheer and by optimization of various other steps in the procedure. As counted by light microscopy of a purified preparation, the number of mechanically-released protoplasts obtained is about 6×104 per gram fresh weight of cortical tissue from the primary root of maize (Zea mays L. WF9×Mo 17) seedlings. Nuclear staining of the preparation, however, shows that about half of these protoplasts lack a nucleus and thus are actually subprotoplasts. Comparison of lectin binding to the plasma membranes of mechanically-and enzymatically-released protoplasts shows that both types contain binding sites forRicinus communis agglutinin. Binding sites for peanut (Arachis hypogaea) agglutinin are not naturally present on mechanically-released protoplasts but are generated by exposure to a mixture of Cellulysin and Pectolyase Y-23, the cell wall-degrading enzymes used to prepare enzymatically-released protoplasts.
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  • 34
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    Protoplasma 165 (1991), S. 11-26 
    ISSN: 1615-6102
    Keywords: Zea mays ; Caffeine ; Microtubules ; Wall thickening ; Stomatal pore opening ; Microtubule organizing centres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Treatment ofZea mays seedlings with a 5 mM caffeine solution inhibits cytokinesis in guard cell mother cells (GMCs), producing unicellular, binucleate aberrant stomata (a-stomata). Ventral wall (VW) strips of limited length, which usually meet the wall portions of GMCs adjoining the cortical zone of the preprophase microtubule band (PMB), are laid down in many a-stomata. In a-stomata with or without VW-strips, the periclinal walls are lined by numerous microtubules (Mts) converging on their mid-region, where local wall thickenings are deposited. When the VW-strips reach the mid-region of the periclinal walls, thickenings lined by numerous Mts rise at their free margins. In certain a-stomata an anticlinal wall column, surrounded by a dense Mt bundle, grows centripetally from either or both of the periclinal wall thickenings. In wall thickenings, the cellulose microfibrils are co-aligned with the adjacent Mts. Pore formation is initiated in all a-stomata. Deposition of an electron dense intra-wall material followed by lysis precedes “pore” opening. This process is closely related to the a-stornata morphogenesis. These observations show that the primary morphogenetic phenomenon in a-stomata is the establishment of an intense and stable polarity in the cytoplasm abutting on the mid-region of the periclinal walls and/or the adjacent plasmalemma area. Prime morphogenetic factor(s), including microtubule organizing centres (MTOCs), seem to function in these sites. Morphogenesis in a-stomata is a Mt-dependent process that is carried out as in normal stomata but in the absence of a VW.
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  • 35
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    Protoplasma 167 (1992), S. 33-42 
    ISSN: 1615-6102
    Keywords: Daucus carota ; Zea mays ; Vigna radiata ; Helicoidal cell walls ; Polylamellate cell walls ; Rapid-freeze deep-etch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper reports on preliminary investigations into the structure of cell walls of varying complexity as revealed by the rapidfreeze deep-etch technique. Three cell types from different species were examined in order to compare the three-dimensional arrangement of random, polylamellate and helicoidal walls. Each cell type displayed a distinctive level of organisation with respect to the cellulose microfibrils and the matrix material. In polylamellated walls, the microfibrils within each layer were linked to each other by 16–20 nm long side chains regularly spaced along the length of the microfibril. In helicoidal walls, the shifting of the microfibrils could cleary be seen, yet no recognisable structures were observed which could mediate this movement.
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  • 36
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    Protoplasma 162 (1991), S. 12-19 
    ISSN: 1615-6102
    Keywords: Zea mays ; Chromium ; Roots ; Cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four inbred lines ofZea mays (33.16, B 68, N 7B, B 77) were grown in nutrient solution to which K2Cr2O7 was added to give final concentration of 5 mg/l Cr (VI). The most evident differences in metal tolerance were observed between the B 68 and 33.16 line: in fact, even though the level of Cr (VI) was almost the same in the root tissues of both lines after 6 d of treatment, in the B 68 line, Cr induced marked alterations of nuclear structure and a progressive arrest of the cell cycle in G 1. In the 33.16 line, on the contrary, the integrity of the nuclei was well preserved and the progression of the cell cycle was only barely affected.
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  • 37
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    Protoplasma 171 (1992), S. 123-133 
    ISSN: 1615-6102
    Keywords: Endosperm ; Floury-2 ; Immunocytochemistry ; Protein bodies ; Zea mays
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    Topics: Biology
    Notes: Summary The seed storage proteins of maize (Zea mays L.) are synthesized during endosperm development on membrane-bound polyribosomes. These proteins, collectively called zeins, are translocated into the lumen of the rough endoplasmic reticulum, where they assemble into protein bodies. Protein body formation in normal genotypes occurs via an ordered deposition of the various types of zeins, and leads to the formation of spherical structures with a diameter of about 1 μm. These structures consist of a central core that contains predominantly α-zein; this central region is surrounded by a peripheral layer of β- and γ-zeins, and the entire structure is bounded by rough endoplasmic reticulum. In the endosperm mutant floury-2 the levels of all classes of zeins are reduced; these kernels exhibit an opaque phenotype instead of the vitreous phenotype observed in normal genotypes. In contrast to the discrete, spherical protein bodies which are formed in normal maize endosperm, the protein bodies within floury-2 endosperm are irregular and the zeins are disorganized; patches of β- and γ-zeins occur within irregularly lobed clusters of α-zein within the lumen of the rough endoplasmic reticulum. The implications of this aberrant distribution are discussed, both with respect to protein body development and kernel characteristics.
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  • 38
    ISSN: 1615-6102
    Keywords: Cytoplasmic calcium ; Fura ; Indo ; Protoplasts ; Gravitropism ; Zea mays
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    Notes: Summary Calcium has been implicated as a key component in the signal transduction process of root gravitropism. We measured cytoplasmic free calcium in protoplasts isolated from the elongation zone and cap of primary roots of light-grown, vertically oriented seedlings ofZea mays L. Protoplasts were loaded with the pentapotassium salts of fura-2 and indo-1 by incubation in acidic solutions of these calcium indicators. Loading increased with decreasing pH but the pH dependence was stronger for indo-1 than for fura-2. In the case of fura-2, loading was enhanced only at the lowest pH (4.5) tested. Dyes loaded in this manner were distributed predominantly in the cytoplasm as indicated by fluorescence patterns. As an alternative method of loading, protoplasts were incubated with the acetoxymethylesters of fura-2 and indo-1. Protoplasts loaded by this method exhibited fluorescence both in the cytoplasm and in association with various organelles. Cytoplasmic calcium levels measured using spectrofluorometry, were found to be 160±40 nM and 257±27 nM, respectively, in populations of protoplasts from the root cap and elongation zone. Cytoplasmic free calcium did not increase upon addition of calcium to the incubation medium, indicating that the passive permeability to calcium was low.
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  • 39
    ISSN: 1615-6102
    Keywords: Endosperm ; Zea mays ; Immunolocalization ; Rough endoplasmic reticulum ; Binding protein ; Protein bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A maize 75 kDa protein recently has been identified as a plant homolog of the mammalian binding protein (BiP). To better understand the function of BiP in protein body formation in maize endosperm, immunomicroscopy studies were conducted on three maize endosperm mutants, floury-2, Mucronate, and Defective endosperm-B 30, in which the level of BiP is highly elevated. Our results showed that protein body morphology in all three mutants was altered. In addition, BiP was localized in both the ER and peripheral regions of the abnormal protein bodies. The degree to which protein body morphology differed from normal was positively correlated with increased amounts of BiP. In addition, the accumulation of BiP in abnormal protein bodies increased with protein body maturation. In the three endosperm mutants, the arrangement of zeins within protein bodies had been perturbed, yet none of the specific zein subclasses exhibited the staining pattern found for BiP. The association of BiP with abnormal packaging of proteins in protein bodies may reflect a biological function to mediate protein folding and assembly in maize endosperm.
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  • 40
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    Molecular genetics and genomics 234 (1992), S. 353-360 
    ISSN: 1617-4623
    Keywords: Zea mays ; Somatic instability ; Bronze-2 ; Genomic shock ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary After epigenetic loss of Mutator activity, the family of Mu elements in Zea mays becomes immobile and highly methylated; in addition, Mu9, the presumptive autonomous regulatory element, is transcriptionally silent and its copy number decreases in successive crosses to non-Mutator lines. Spontaneous reactivation, scored as restoration of somatic instability of potentially mutable alleles of Bronze-2, of such cryptic Mutator lines is rare, occurring with a frequency of about 10−4. Irradiation of pollen with 254 nm ultraviolet light increases reactivation rate in the progeny kernels by up to 40-fold. Accompanying reactivation, the copy number of Mu9 elements increased, two-fold in one line and 20 to 40-fold in a second line. Reactivation may involve direct DNA damage or immediate physiological stress in the treated pollen.
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  • 41
    ISSN: 1617-4623
    Keywords: Flavonoids ; Light regulation ; Sn locus ; Tissue-specificity ; Zea mays
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    Notes: Summary The Sn locus of maize is functionally similar to the R and B loci, in that Sn differentially controls the tissue-specific deposition of anthocyanin pigments in certain seedling and plant cells. We show that Sn shows molecular similarity to the R gene and have used R DNA probes to characterize several Sn alleles. Northern analysis demonstrates that all Sn alleles encode a 2.5 kb transcript, which is expressed in a tissue-specific fashion consistent with the distribution of anthocyanins. Expression of the Sn gene is light-regulated. However, the Sn: bol3 allele allows Sn mRNA transcription to occur in the dark, leading to pigmentation in dark-grown seedlings and cob integuments. We report the isolation of genomic and cDNA clones of the light-independent Sn: bol3 allele. Using Sn cDNA as a probe, the spatial and temporal expression of Sn has been examined. The cell-specific localization of Sn mRNA has been confirmed by in situ hybridization using labelled antisense RNA probes. According to its proposed regulatory role, expression of Sn precedes and, in turn, causes a coordinate and tissue-specific accumulation of mRNA of structural genes for pigment synthesis and deposition, such as A1 and C2. The functional and structural relationship between R, B, Lc and Sn is discussed in terms of an evolutionary derivation from a single ancestral gene which gave rise this diverse gene family by successive duplication events.
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  • 42
    ISSN: 1617-4623
    Keywords: Zea mays ; Transposable elements ; Opaque-2 ; Waxy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The two components of theBg-rbg transposable element system of maize have been cloned. TheBg element, isolated from the mutable allelewx-m32 :: Bg is inserted in the intron of theWaxy (Wx) gene between exons 12 and 13. The length of the element is of 4869 bp.Bg has 5 by terminal inverted repeats, and generates upon insertion an 8 by direct duplication of the target sequence. Both ends of theBg element contain a 76 by direct repeat adjacent to the terminal inverted repeats. The hexamer motif TATCGkC G is here repeated several times in direct or inverse orientation. Therbg element was isolated from the mutable alleleo2m(r) where it is located in the promoter region of theOpaque-2 (O2) gene.rbg is approximately 4.5 kb in length, has terminal inverted repeats identical to those of theBg element, and is also flanked by an 8 by direct duplication at the target site. LikeBg, rbg carries the 76 by direct repeats. Restriction enzyme analysis reveals that, compared toBg, the receptor element is distinguishable by small deletion and insertion events. Sequence data indicate that not more than 75% homology exists at the DNA level between therbg element and the autonomousBg element.
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  • 43
    ISSN: 1617-4623
    Keywords: Lysine biosynthesis ; Feedback regulation ; Zea mays ; Genetic complementation
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Dihydrodipicolinate synthase (DHPS; EC 4.2.1.52) is the first committed enzyme in the lysine branch of the aspartate-derived amino acid biosynthesis pathway and is common to bacteria and plants. Due to feedback inhibition by lysine, DHPS serves in a regulatory role for this pathway in plant metabolism. To elucidate the molecular genetic characteristics of DHPS, we isolated a putative full-length cDNA clone for maize DHPS by direct genetic selection in an Escherichia coli dapA −auxotroph. The maize DHPS activity expressed in the complemented E. coli auxotroph showed the lysine inhibition characteristics of purified maize DHPS, indicating that the cDNA encoded sequences for both the catalytic function and regulatory properties of the enzyme. The N-terminal amino acid sequence of purified maize DHPS was determined by direct sequencing and showed homology to a sequence within the cDNA, indicating that the clone contained the entire coding region for a mature polypeptide of 326 amino acids plus a 54 amino acid transit peptide sequence. The molecular weight of 35854, predicted from the deduced amino acid sequence, was similar to the 38 000 Mr determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) for the purified enzyme from maize. DHPS mRNAs complementary to the cDNA were detected in RNA isolated from developing maize endosperm and embryo tissues. Southern blots indicated the presence of more than one genomic sequence homologous to DHPS per haploid maize genome.
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  • 44
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    Molecular genetics and genomics 229 (1991), S. 161-174 
    ISSN: 1617-4623
    Keywords: Zea mays ; transposable element ; Uq activation ; Uq cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allelism tests between the standard Uq element (Uq1) and five newly activated germinal Uq elements (Uq2, Uq3, UQ4, Uq5, and Uq6) demonstrate that these new Uq elements are independent of Uq1. Gametes that either contain one Uq or various combinations of two different and phenotypically distinguishable Uq elements, have been constructed either with or without the a-ruq reporter allele. Genetic analyses of the progenies of the gametes (using the standard a-ruq tested line as the other parent) have indicated that (i) each Uq element, when present alone, has the capacity to express full activity except when a secondary transposition or loss of activity has occurred; (ii) all five new Uq elements are independent of Uq1 with respect to transposition activity; and (iii) these newly originated Uqs are clustered on one linkage group. Uq2 is allelic to Uq4, and Uq3 is allelic to Uq5, whereas Uq6 is linked to both allelic pairs. A putative linkage map of these Uq elements is presented. In reciprocal crosses there is a striking difference in phenotypic segregation of Uq; when transmitted via the male parent Uq loses full expression capacity.
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    Molecular genetics and genomics 233 (1992), S. 379-387 
    ISSN: 1617-4623
    Keywords: Bz2 gene ; Transcriptional regulation ; Anthocyanin pathway ; Transient assay ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The putative maize transcription factor genes R and C1 are required for expression of reporter genes with promoters from the Bz1 and A1 genes, which encode enzymes required for anthocyanin biosynthesis in maize. Bz2 is another anthocyanin biosynthetic gene; we show that expression of a reporter gene from the Bz2 promoter also requires R and C1 when the fusion construct is introduced into maize kernels by particle gun bombardment. When electroporated into maize protoplasts from a suspension cell line not synthesizing anthocyanins, reporter genes with Bz2, Bz1, and A1 promoters are expressed only when both R and C1 expression plasmids are co-electroporated. Electroporation of R and C1 expression plasmids also induces the endogenous genes required for anthocyanin synthesis, resulting in pink protoplasts within 24 h. RNase protection analysis demonstrates that accumulation of mRNA from the endogenous Bzl and Bz2 genes absolutely requires introduced R and C1. In time-course experiments there is a delay of 3–6 h before the Bz2 promoter is activated, supporting the proposed role for R- and C1-encoded proteins in transcriptional control. An excess of R relative to C1 suppresses expression of A1, Bz1, and Bz2 promoters, suggesting an interaction between the R and C1 proteins.
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    Molecular genetics and genomics 233 (1992), S. 388-394 
    ISSN: 1617-4623
    Keywords: Viral vector ; Transposable element ; Zea mays ; Agroinfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously shown that the maize transposable element Ds1 introduced into maize plants by agroinfection can be excised from the genome of geminivirus maize streak virus (MSV). Excision depended strictly on the presence of an active Ac element in the plants. In this study, the excision products or “footprints” left in the MSV genome after Ds1 excision were extensively characterized and the effects of flanking sequences on Ds1 excision were analysed. Most types of footprints obtained were comparable to those described for Ds1 excision in the maize genome, and could be explained by the models proposed for excision of plant transposable elements. In two revertants, however, some terminal sequences of the Ds1 element were found to have been left behind at the excision site. The finding of this novel type of Ds1 footprint indicated that gene conversion events occurred during and/or after Ds1 excision from the MSV genome. A partial deletion of one copy of the 8 by duplications flanking the Ds1 element had no effect on the frequency or on the types of footprints of Ds1 excision from the MSV genome. Thus, the duplicated 8 by sequences flanking the transposable element are not involved in Ds1 excision. These results, as well as a statistical analysis of the modifications of the bases flanking the Ds1 element after excision, are discussed in terms of excision models.
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  • 47
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    Molecular genetics and genomics 231 (1992), S. 369-374 
    ISSN: 1617-4623
    Keywords: Zea mays ; Transcription ; Transformation ; Endosperm ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 43 by fragment containing the — 300 region upstream control element common to the endosperm expressed zein genes of Zea mays L. has been analyzed by in vivo and in vitro techniques. Transient transformation studies with protoplasts from a maize endosperm culture indicate that the element positively affects CaMV 35S promoter-driven gene expression, and that this effect is both orientation- and position-dependent. Band-shift and Southwestern blotting experiments demonstrate that the element is specifically bound by different sets of DNA-binding proteins from seedling and endosperm nuclei. A 2 by substitution within the most conserved region of the element both reduces the stimulatory effect on transcription and alters the binding of nuclear proteins from both tissues.
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  • 48
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    Molecular genetics and genomics 233 (1992), S. 269-277 
    ISSN: 1617-4623
    Keywords: Zea mays ; Bz2 locus ; Natural antisense transcripts ; Transposable elements ; Gene family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Analysis of the transcription pattern of theBz2 locus revealed that overlapping transcripts are derived from opposite DNA strands. The most abundant transcript (sense transcript) has an open reading frame coding for a protein of 241 amino acids, whilst in the antisense orientation no open reading frame has been detected; the antisense transcripts are detected only in those tissues that show high levels of sense transcript. Particle gun experiments indicate that the sense transcript is sufficient to provide theBz2 function. The promoter driving the sense transcript contains the elements usually found in front of eukaryotic genes. In addition an element with similarity to theC1 andR binding sites identified in theBz1 promoter is found. Further upstream in the promoter region a transposon-like insertion has been identified. This element has features similar to members of theAc/Ds transposable element family. The putativeBz2 protein shows similarity to various other plant proteins and to anEscherichia coli protein. All related proteins have in common the fact that they are involved in stress responses.
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  • 49
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    Molecular genetics and genomics 225 (1991), S. 81-93 
    ISSN: 1617-4623
    Keywords: Enhancement ; Intron ; Splicing ; Transient assay ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The inclusion of the alcohol dehydrogenase 1-S (Adh1-S) intron 1 in the transcription unit of maize gene constructs has been shown to increase gene expression in cultured maize cells. We have extended these studies with Adh1-S intron 1 using the firefly luciferase, Escherichia coli β-glucuronidase and chloramphenicol acetyltransferase reporter genes adjoined to different plant promoters and find enhancement of transient gene expression in all cases but one. We also show that the enhancement phenomenon can be mediated by the third intron of the maize actin gene. In all cases tested, the inclusion of an intron results in increased levels of steady-state RNA. The degree of enhancement depends on the exon sequences flanking the intron; flanking exons also influence the efficiency of intron splicing. Unexpectedly, unspliced RNAs accumulate during the transient assay.
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  • 50
    ISSN: 1617-4623
    Keywords: Transposase ; DNA-binding protein ; Zea mays ; mobile DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The 3.5 kb long mRNA of the maize transposable element Ac contains an open reading frame (ORFa) which encodes a polypeptide of 807 amino acids, the putative transposase of Ac. The Ac mRNA is a rare transcript: we now estimate the fraction of Ac mRNA in wx-m7::Ac seedlings to be 2–13 × 10−5 of the polyA RNA. Assuming that maize cells contain similar amounts of polyA RNA as another monocot (0.16 pg/cell), this is equivalent to 1.5–10 transcripts in each cell. A protein with an apparent molecular weight of 112 kDa is detected, by five antisera directed against different segments of ORFa, exclusively in nuclear extracts from Ac-containing maize. This protein is most likely the full-length Ac ORFa protein. We estimate its concentration to be in the range of 3 × 10− of the nuclear proteins, or about 1000 molecules per triploid endosperm cell containing one Ac element.
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  • 51
    ISSN: 1617-4623
    Keywords: Phosphoenolpyruvate carboxylase ; DNA binding protein ; Zea mays ; C4 plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A plant nuclear protein PEP-I, which binds specifically to the promoter region of the phosphoenolpyruvate carboxylase (PEPC) gene, was identified. Methylation interference analysis and DNA binding assays using synthetic oligonucleotides revealed that PEP-I binds to GC-rich elements. These elements are directly repeated sequences in the promoter region of the PEPC gene and we have suggested that they may be cis-regulatory element of this gene. The consensus sequence of the element is CCCTCTCCACATCC and the CTCC is essential for binding of PEP-I. PEP-I is present in the nuclear extracts of green leaves, where the PEPC gene is expressed. However, no binding was detected in tissues where the PEPC gene is not expressed in vivo, such as roots or etiolated leaves. Thus, PEP-1 is the first factor identified in plants which has different binding activity in light-grown compared with dark-grown tissue. PEP-I binding is also tissue-specific, suggesting that PEP-1 may function to coordinate PEPC gene expression with respect to light and tissue specificity. This report describes the identification and characterization of the sequences required for PEP-1 binding.
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  • 52
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    Plant and soil 132 (1991), S. 159-163 
    ISSN: 1573-5036
    Keywords: enzymatical conversion ; organic-acid secretion ; proton secretion ; rhizosphere ; roots ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The participation of organic acids in the process of soil acidification was related to other H+ pumping processes. The ratio between efflux of organic acids and proton secretion of maize roots was determined with the use of a pH-stat combined with a collecting system for organic acids. Changes in the composition of carboxylic acids influenced by nitrogen supply were monitored by HPLC and via enzymatic conversion. The following substances were found to be secreted by maize roots: glycolate, glyoxylate, fumarate, 2-oxoglutarate and oxalate. Malate, however, could not be detected. There is no organic acid dominantly secreted by the roots, but changes are observed during aging which might result from deficiencies of nutrients e.g. P. Fertilization of N-deficient plants with urea leads to a significant change in the composition of acids secreted. In this case, oxalate was additionally detected with a concomitant increase in glyoxylate, indicating important changes in metabolism. Acidification of the rhizosphere is predominantly maintained by secretion of protons, not by efflux of organic acids, which contributed 0.2 to 0.3% to this process only. The role of organic acids in nutrient uptake is discussed.
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  • 53
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    Plant and soil 144 (1992), S. 199-205 
    ISSN: 1573-5036
    Keywords: acid phosphatase ; ectoenzymes ; naphthyl phosphate ; Picea abies ; rhizosphere ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract For in vivo demonstration of acid phosphatase activity in the rhizosphere of soil-grown plants filter papers were treated with a mixture of 1-naphthyl phosphate as substrate and the diazonium salt Fast Red TR as an indicator. After enzymatic hydrolysis, 1-naphthol forms a red complex with Fast Red TR. This method was applied to 8-day old maize plants and 3-year old Norway spruce plants growing in rhizoboxes in soil under non-sterile conditions. The treated filter paper is placed at the surface of roots and soil and acid phosphatase activity is visualized as a red-coloured ‘root print’ on the filter paper. The method can be used as a qualitative analysis of acid phosphatase in the rhizosphere. It also allows a rough estimate of phosphatase activity in different root zones.
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  • 54
    ISSN: 1573-5060
    Keywords: Breeding ; heritability ; in vitro digestibility ; in vivo digestibility ; maize ; silage maize ; variation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation and covariation for agronomic and digestibility traits of silage maize are reported from a compilation of 22 years of experiments with standard sheep. Genotype effects of DOM and DCF were highly significant, even when genotypes were nested in earliness groups or brown-midrib hybrids discarded (Table 2). The genetic variance of crude fiber content was low, but the variance of the DCF was high. The genetic variance of DOM was about 4 times lower than genetic variance of DCF, but broad sense heritability of DOM was higher because of lower residual variance (Table 3). Genetic correlations between grain or crude fiber content and DOM had similar absolute values, 0.65, so each of these two traits was an important but not the unique determinant of silage maize quality. There was no correlation between DCF and grain or crude fiber content. Yield was not related to DOM or DCF within each group of earliness, allowing some quality improvement without agronomic drift (Table 4). Except for late hybrids, most of DOM differences between groups of earliness came from lowering of minimum value, while maximum values were similar. It was the contrary for DCF, with similar minimum values for all groups (Table 5). There was no obvious correlation between year of registration of hybrids and DOM or DCF, but extra new variation seemed obtained only for low values (Figs 1, 2; Table 6). IVDOM according to the APC process was a poor predictor of DOM, especially when brown-midrib hybrids and earliness effects were discarded; but because heritability of this trait was similar to DOM heritability, such enzymatic processes could probably be used to avoid drift towards poor DOM with hybrids bred for higher stalk strength.
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  • 55
    ISSN: 1573-5060
    Keywords: Zea mays ; forage maize ; stover ; nutritive value ; heritability ; quantitative inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The maize populations BS13 (S2) C4 and Lancaster are compared with respect to their potential as forage maize. In light of the preliminary results, the Lancaster population was chosen for a more thorough study. The determination of NDF gave a sufficiently precise estimate of the stover digestibility within our experimental conditions. The heritability of stover and grain production was 0.59 and 0.30, respectively, whilst that of the stover NDF was 0.32. The additive genetic correlation between NDF and stover production, possibly attributable to the architecture of the plant, favours the selection of genotypes that produce more and better forage.
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  • 56
    ISSN: 1573-5060
    Keywords: Zea mays ; maize accessions ; teosinte ; mature pollen ; heat tolerance ; pollen tube length ; pollen viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of high temperature on mature pollen of various maize lines were investigated. Genotypic differences in pollen reaction to high temperature were revealed. Pollen grains resistant to high temperature (35°C, 26°C) were characterized by higher germination capacity and better ability to develop normal pollen tubes. The studies are of interest to evaluate reproductive system tolerance and conduct gamete selection at the mature pollen grain stage in maize.
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  • 57
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    Euphytica 56 (1991), S. 97-105 
    ISSN: 1573-5060
    Keywords: growth regulators ; dimethyl sulfoxide ; Zea mays ; apomixis ; chemical induction ; maize seed set
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Silks of 18 maize (Zea may L.) F1 hybrids were treated with different combinations of 9 growth regulators, colchicine, and dimethyl sulfoxide (DMSO) for the purpose to induce apomixis (agamospermy) in 1988 and 1989. Hybrid K301 × K303 gave the highest (0.36%) average frequency of seed induction among the hybrids. The most effective treatments were DMSO, gibberellic acid plus 6-benzyl aminopurine (6-BA), and DMSO plus methanesulfonic acid. Individually, the highest frequency of seed induction was 1.4% for hybrid K731×K306 when treated with α-naphthalene acetic acid (NAA)-zeatin mixture. The frequency of seed induction seemed to depend partially on the interaction between chemicals and hybrids. Cytological observation of root-tip cells indicated that the majority of the seeds obtained were diploid, some were mixoploid, and a few were haploid. Diploid plants from induced seeds from the same parent were morphologically uniform and resembled the parent. Variations in plant and ear heights were comparable to those of the hybrid parent. Cytological and morphological investigations suggested that the chemically induced seeds originated mainly from somatic tissue but occasionally came from reduced cells in the embryo sac, leading to haploids. The results showed that chemical induction of adventitious embryony in maize hybrids is possible, but the more effective chemicals, their concentrations, and ways of application for increasing the frequency of seed induction need to be explored for practical use.
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  • 58
    ISSN: 1573-5060
    Keywords: cold tolerance ; correlated responses ; germination ; kernel type ; kernel weight ; recurrent selection ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Four cycles of divergent full-sib recurrent selection for the ability to germinate at low temperature were conducted in a maize (Zea mays L.) F2 population. The selection criterion was the high (H) or the low (L) value in algebraic terms of the difference (DG) between germination percentage at 9.5°C (G9.5) detected 19 days after sowing and germination percentage at 25°C (G 25) seven days after sowing; both traits were evaluated in a controlled environment (germinator). Direct and correlated responses estimated during the course of selection were in accordance with those evaluated at the end. Selection for H led to populations with higher DG values, while the reverse was noted for L; differences between H and L populations increased in successive selection cycles, though divergence tended to level off. Selection for H also resulted in higher G 9.5 (day 19), shorter germination time and more flinty kernels, while selection for L led to responses in the opposite direction as well as to a lower G 9.5 detected 37 days after sowing (i.e. at the end of germination). In contrast, responses were negligible for G 25 and varied erratically from one cycle to another for kernel weight.
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  • 59
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence induction ; field studies ; Helianthus annuus ; Phaseolus vulgaris ; photoinhibition ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It was tested whether field-grown plants (Phaseolus vulgaris, Zea mays and Helianthus annuus) reflect photoinhibitory effects under natural conditions. Attached leaves were used for determination of the photochemical capacity of Photosystem II (Fv/Fm) by means of a portable fluorimeter (PSM, BioMonitor, S.). For a more qualitative description of Fv/Fm, the modifications of the absolute values F0, Fm as well as of the half-rise time of Fm (T/2) were also considered. By comparing artificially shaded and ‘sun exposed’ plants, the direct influence of light on the photochemical capacity was investigated. Under low natural light conditions the differences of the photochemical capacity between shaded and ‘sun exposed’ leaves were negligible in all three species. On a day with full sunlight a decline of Fv/Fm was observable at noon-time in the ‘sun exposed’ leaves of all three species, although the absolute values differed between the species compared. Additionally, the extent of the recovery of Fv/Fm was varying. Both phenomena could be due to differences in the photosynthetic apparatus (e.g., C3−C4, ontogenetic stage, sun-shade type), to self-shading phenomena (comparing leaf layers of Zea and Helianthus) or to differences in the activity of repair mechanisms possibly caused by other environmental factors (vapour pressure deficit = VPD, drought and temperature phenomena). Nevertheless, the results of the shading experiments and the comparison of species lead to the conclusion that primarily light-induced reduction of the photochemical capacity appears at noon in leaves exposed to full sunlight, a partial restoration of Fv/Fm takes place till the evening. Artifically shaded plants show only a slight alteration of the photochemical capacity.
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  • 60
    ISSN: 1573-5036
    Keywords: fumigation ; Glomus intraradices ; G. vesiculiferum ; G. versiforme ; Glycine max, grass-legume mixture ; 15N ; nitrogen transfer ; soil microorganisms ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of mycorrhizal inoculation on 15N transfer from soybean to maize was studied in fumigated and non-fumigated soil. Three Glomus species and a non-inoculated control were compared. In spite of higher levels of root colonization and more abundant hyphae associated with plants growing in fumigated soil, mycorrhizae-enhanced 15N transfer to maize was significant only in non-fumigated plots. High 15N transfer was not only associated with high mycelium density in soil but also with low soil microbial carbon, suggesting that the effect of mycorrhizal fungi on soil microbial populations may be an important factor affecting N transfer between mycorrhizal plants.
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  • 61
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    Plant cell, tissue and organ culture 28 (1992), S. 129-137 
    ISSN: 1573-5044
    Keywords: cms-T ; in vitro selection ; methomyl resistance ; mitochondrial mutation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several factors affecting the success of selection in plant populations were examined for their relevance to in vitro selection. Three in vitro selection schemes and two growth assessment procedures were evaluated for effectiveness in selecting for a mitochondrial trait in maize: resistance to the insecticidal compound methomyl. Regenerable maize callus was derived from immature embryos of the three-way hybrid P39/IL766A2 x W182BN containing Texas male sterile cytoplasm (cms-T). Either low, gradually increasing, or high selection pressures were used to grow callus over a period of 3–5 months. There was no significant difference in recovery of resistant plants using these 3 methods. Growth of callus on medium containing methomyl was assessed by increase in fresh weight during the final month of selection or by increase in number of callus pieces over the course of selection. These quantitative measures of growth were unreliable indicators for gain in resistance within the callus population. A procedure for recovery of methomyl resistant and male-fertile cms-T plants is suggested.
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  • 62
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; genetic variation ; nitrate accumulation ; N use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The objective of this research was to obtain information about expression of genes controlling N concentration in the lower stalk internodes of maize at silking stages and in two other stages during the grain filling period. The inheritance of nitrate-N concentration, total N concentration, and the nitrate-N/total N ratio in the lower stalk internodes was measured in an eight-line diallel cross experiment and in an experiment involving segregating generations. The results show that the parameters examined, particularly nitrate-N concentration, are genetically controlled and that maize plants differ in this respect. Moreover, the magnitude of the general combining ability effects in relation to the size of specific combining ability obtained from the diallel analysis and the mean squares of the analysis of variance of generation means indicated additive heritability of nitrate-N concentration and other N-related traits in maize stalks. These findings suggest to us that a cyclic selection program in maize should be effective in modifying the level of N-related traits concentration in the stalks.
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  • 63
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; prediction ability ; discrimination ability ; yield ; digestibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The identification of environments suitable for selection should enable plant breeders to test reliably a larger number of genotypes with given resources. This research was undertaken to evaluate discrimination ability (DA) and prediction ability (PA) of eight environments involving two locations. Eckartsweier (Eck) 1 and Voelkenrode (Voe); 2 yer. 1984 (84) and 1985 (85); and two harvests, silage harvest (I) and later (II). It was based on dry matter yield of plant (PDMY), ear (EDMY) and stover (SDMY) and on in vitro digestible organic matter (IVDOM), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) of stover of 12 inbred lines and their 66 diallel crosses in maize (Zea mays L.). Linear regression coefficient of the performance of genotypes in an environment on that averaged across all environments and its degree of determination were used as measures of the DA and PA of environments, respectively. In hybrids, the DA of environments differed significantly for all traits except SDMY and ADL. Environment Eck851 showed better PA (≥0.63) than other environments for PDMY, EDMY, IVDOM, NDF, and ADF. Among the 12 two-environment combinations. EckI was a better predictor for PDMY, EDMY, IVDOM and NDF (PA≥0.80). The more productive environments showed better DA and PA for PDMY and FDMY than less productive ones. For IVDOM and NDF the first harvest provided better discrimination and prediction than the second harvest. In inbred lines the DA of environments differed significantly for EDMY only. In the present study, PA and DA seemed to be functions of the environments, PA was improved by combining two environments, and some environments seemed to be suitable for preliminary selection of genotypes for such diverse traits as yield and digestibility.
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  • 64
    ISSN: 1573-5079
    Keywords: drought ; fluorescence quenching ; gas exchange ; Helianthus annuus ; patchiness ; Phaseolus vulgaris ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas exchange and fluorescence measurements of attached leaves of water stressed bean, sunflower and maize plants were carried out at two light intensities (250 μmol quanta m-2s-1 and 850 μmol quanta m-2s-1). Besides the restriction of transpiration and CO2 uptake, the dissipation of excess light energy was clearly reflected in the light and dark reactions of photosynthesis under stress conditions. Bean and maize plants preferentially use non-photochemical quenching for light energy dissipation. In sunflower plants, excess light energy gave rise to photochemical quenching. Autoradiography of leaves after photosynthesis in 14CO2 demonstrated the occurrence of leaf patchiness in sunflower and maize but not in bean. The contribution of CO2 recycling within the leaves to energy dissipation was investigated by studies in 2.5% oxygen to suppress photorespiration. The participation of different energy dissipating mechanisms to quanta comsumption on agriculturally relevant species is discussed.
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  • 65
    ISSN: 1573-5044
    Keywords: cell cycle ; DNA content ; embryogenic competence ; flow cytometry ; mitotic activity ; somatic embryogenesis ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic competence of maize (Zea mays L.) leaf tissues was studied with regard to leaf age, distance from leaf base, mitotic activity, 2C nuclear DNA content, and the distribution of cells within the cell cycle. The highest embryogenic competence was observed in the first segment of the second innermost leaf. In a succession of 8 mm segments from the leaf base, the frequency of cells in the G0/G1 phase of the cell cycle and mitotic activity decreased with leaf age and with the distance from leaf base. No significant differences in 2C nuclear DNA content were found for leaf segments of different age and position. The mean 2C nuclear DNA content was 5.74 pg. The results suggested that the loss of embryogenic competence in mature maize leaf tissues is not related to changes in nuclear DNA content, and that the competence is not simply related to a certain distribution of cells within the cell cycle or to a certain level of mitotic activity.
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  • 66
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    Journal of chemical ecology 18 (1992), S. 1981-1990 
    ISSN: 1573-1561
    Keywords: Allelopathy ; ferulic acid ; amylase ; maltase ; invertase ; acid protease ; acid phosphatase ; Zea mays ; growth ; root ; shoot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ferulic acid was tested for its effect on the growth of root and shoot, fresh and dry weights, and hydrolytic enzyme activities of germinating maize seeds. The results showed that root growth was inhibited more than shoot growth. A significant reduction in the activities of hydrolytic enzymes was also observed, which reflects a mechanism of action for the natural growth inhibitors, which may include other phenolic compounds.
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  • 67
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    Journal of chemical ecology 18 (1992), S. 897-905 
    ISSN: 1573-1561
    Keywords: Pollen ; corn ; Zea mays ; teosinte ; Zea mexicana ; allelopathy ; phenylacetic acid ; phytotoxicity ; Amaranthus leucocarpus ; Echinochloa crusgalli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phenylacetic acid (PAA), one of the phytotoxic compounds in corn (Zea mays) pollen, was identified by GC-MS and by direct comparison with a pure commercial sample of PAA. Bioassays were carried out by testing whole pollen, methylene chloride extract of the pollen, and pure PAA on germination and radical growth ofAmaranthus leucocarpus andEchinochloa crusgalli. The effect of corn pollen was compared with that ofZea mexicana (Teosinte), one of the wild relatives of cultivated maize.
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  • 68
    ISSN: 1573-5060
    Keywords: coancestry coefficient ; genetic similarity ; maize ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In this study, 31 elite inbred lines of maize (Zea mays L.) were analyzed with 149 clone-enzyme combinations for their respective RFLP profiles. Objectives were (1) to determine the utility of RFLPs for estimation of genetic similarties among 16 inbred lines from the Iowa Stiff Stalk Synthetic (BSSS) and among 15 inbred lines from the Lancaster Sure Crop (LSC) heterotic groups and (2) to compare genetic similarities based on molecular markers with those based on pedigree information. Coefficients of genetic similarity (GS) and coancestry (f) between pairs of lines from the same heterotic group were calculated from RFLP and pedigree data, respectively. For lines from the BSSS heterotic group, cluster analyses based on RFLP and pedigree data revealed similar associations. GS and f values were closely correlated (r=0.70) for related BSSS lines. For lines from the LSC heterotic group, considerable discrepancies existed between the GS and f values, especially for those pairs involving inbreds Va22 and Lo924. Effect of selection and/or erroneous pedigree records are discussed as possible explanations for the low correlation of GS and f values (r=0.07) for related LSC lines. RFLPs seem useful for investigation of relationships among maize inbreds, verification of pedigree records, and quantification of the degree of relatedness.
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  • 69
    ISSN: 1573-5060
    Keywords: androgenesis ; in vitro culture ; maize ; microspores ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The capacity of the maize genotype 4c1 to regenerate microcalli and embryos from cultured microspores has been examined by comparing various cold pretreatments and culture media, using microspores and pollen at different stages of development. Viability of cultured cells was tested with FDA and their development was traced with light and fluorescence microscopy using DAPI as a nuclear dye. It was found that a pre-incubation of dissected flowers floating in a liquid nutrient medium at 8°C during 10–14 days was most successful for the induction of cell division. Among the developmental stages tested only the microspores appeared to regenerate. Subculture at 25°C in the same liquid medium, supplemented with 0.1 mg/l TIBA, gave highest rates of microspore division, i.e. up to 70% at 4 to 6 days of culture. All pathways described earlier for maize androgenic embryogenesis were observed within the 4c1 genotype. Symmetric divisions occurred in cultured microspores but most frequently asymmetric divisions lead to the formation of microcalli within 12 days of culture. In at least 60% of all dividing microspores cells were derived from the generative nucleus. Microcalli further developed either into loose or compact calli. Compact calli formed embryo-like structures.
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  • 70
    ISSN: 1573-5060
    Keywords: population improvement ; maize ; Zea mays ; honeycumb selection ; adaptability ; stability ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study was undertaken to investigate the implications of genotype x soil texture interaction on response to selection in maize. Mass honeycomb selection for yield was applied for 11 cycles from the F2 of the single cross maize hybrid F68×NE2 in a field B with silty-clay-loam soil texture. Response to selection compared to the original single cross hybrid was estimated both in absence of competition and under solid stand in the selection field B and in a nearby field A differing in soil texture (clay-loam). A strong crossover type of interaction occurred both under solid stand and in the absence of competition in the two tests the improved population outyielded the hybrid in field B in the two densities, but lagged behing the hybrid in field A. The results suggest that interaction between genotype and soil texture might affect efficiency of selection detrimentally unless provision is taken for parallel selection early in the crop improvement program in fields differing in soil texture.
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  • 71
    ISSN: 1573-5060
    Keywords: doubled haploid ; genetic marker ; wheat ; wheat x maize crosses ; Triticum aestivum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat doubled haploid (DH) lines were produced from the F1 hybrid, Fukudo-komugi x Oligo Culm, through intergeneric crosses between wheat and maize. F2 plants and 203 DH lines were analyzed for the segregation of the eight genetic markers, namely, grain proteins, grain esterases, GA-insensitivity and glume traits. The segregation in the F2 plants fitted to the expected ratios. No deviation was observed among the DH lines, either, except for the glume pubescence. The result indicates the absence of correlation between the markers investigated and the efficiency of embryo formation in the DH lines.
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  • 72
    ISSN: 1573-5060
    Keywords: forage maize ; Zea mays ; breeding ; nutritive value ; cell-wall digestibility ; stalk quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The current study deals with genetic improvement of the nutritive value of forage maize. In separate field trials, maize inbred lines without the brown midrib trait and derived hybrids were evaluated for stalk quality as well as some other agronomic traits. The aim was to relate the performance of lines and hybrids. Quality traits studied were the contents of ash and cell walls expressed as percentage of dry matter and the digestibilities of organic matter and cell walls (stalk-dv% and stalk-dcw%, respectively). The performance of hybrids was established in a trial at two locations with three replicates per location and the performance of lines at one location in an unreplicated trial. The range for stalk-dcw% was about 10 percentage units between hybrids and 15 percentage units between inbred lines. Stalk-dcw% had of all quality traits of hybrids the highest broad-sense heritability (h 2=0.74), and determined about 80% of the variation in stalk-dv%. The only stalk quality trait where a significant correlation was found between the mean hybrid performance and the corresponding midparent value was stalk-dcw% (r=0.70, P〈0.01). In conclusion, stalk-dcw% proved to be the only stalk quality trait worth evaluating at the inbred line level in a breeding programme aimed at producing commercial hybrid varieties of forage maize.
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  • 73
    ISSN: 1573-5060
    Keywords: cluster analysis ; principal component analysis ; accession ; landraces ; Zea mays ; maize ; dendrogram ; variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two multivariate techniques were used to characterize 30 maize accessions collected from three ecological zones of Bendel State, Nigeria. Differentiation of the 30 accessions into five distinct groups was achieved with the unweighted variable group method of the average linkage cluster analysis of 34 agronomic characters. Four of the taxonomic groups contained at least three accessions each, while a fifth group contained only one. The single accession contained in the fifth group was characterised by very early maturity, deeply pigmented leaves and ear husks and short statured plants. Clustering of the accessions into different phenetic groups followed substantially along geographical and traditionally trading routes. A few cases of overlapping of accessions from different geographical locations were obtained. Principal component analysis revealed that days to 50% tasseling and silking, number of nodes/plant, ear length, ear weight, leaf width, and kernel colour were the principal discriminatory characters that differentiated the accessions. Sixty-four percent of the total variation among the 34 characters were accounted for by the first five principal components while the first and second components accounted for 26 and 14 respectively.
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  • 74
    ISSN: 1573-5087
    Keywords: Mitochondria ; respiration ; seed ageing ; seed storage ; temperature ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper reports on a study of mitochondrial activity in etiolated shoots of freshly harvested and moderately aged kernels of maize. Activity was investigated after incubation at a favourable temperature (25°C), sub-optimal temperature (13°C) and after a heat shock (46°C for 2h). Although impaired mitochondrial activity in shoots from moderately aged maize kernels was not detected at 25°C, deficiencies became evident under low temperature stress (13°C). State 3 oxygen uptake, cyanide-insensitive oxygen uptake and cytochrome oxidase activity were lower in mitochondria from these shoots at 13°C than in mitochondria from shoots of freshly harvested kernels at this temperature. After a heat shock, cyanide-insensitive oxygen uptake was higher, and cytochrome oxidase activity lower, in shoots of aged kernels than in shoots of fresh kernels. No significant differences in ADP: O ratio or succinate dehydrogenase activity occurred between mitochondria from shoots of the two seed lots in any of the temperature treatments.
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  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 18 (1992), S. 931-944 
    ISSN: 1573-1561
    Keywords: Diabrotica virgifera virgifera ; 6-methoxy-2-benzoxazolinone ; hydroxamic acids ; semiochemical ; attractants ; western corn rootworm ; host location ; Coleoptera ; Chrysomelidae ; Zea mays ; kairomone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A bioassay-driven sequential fractionation scheme was used to isolate all portions of a crude dichloromethane corn seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. 6-Methoxy-2-benzoxazolinone (MBOA) was identified as one of the most important components of an attractive crude corn extract. MBOA was found on or in the intact root tissues by injecting an extract of undamaged roots onto an HPLC immediately after extraction. MBOA was demonstrated to be volatile and functions as a semiochemical in conjunction with carbon dioxide in host location by western corn rootworm larvae, which are oligophagous on the roots of maize and several other species of grasses. Because MBOA occurs almost exclusively in maize and other grasses, it offers a simple way for the larvae to distinguish possible hosts from non-hosts. MBOA has previously been reported as a chemical defense against other insect species. This is the first report in grasses of a secondary compound that is toxic or a deterrent to nonadapted insect herbivores but that is used as a semiochemical in host location by a specialist insect species.
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  • 76
    ISSN: 1573-8248
    Keywords: Beauveria bassiana ; Ostrinia nubilalis ; endophytic relationship ; biological control ; insect pathology ; Zea mays ; Beauveria bassiana ; Ostrinia nubilalis ; lutte biologique ; relation endophyte ; pathologie de l'insecte ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le champignon entomopathogène,Beauveria bassiana (Balsamo) Vuillemin a été épandu sur maïs, au stade cornet (V7) par application foliaire d'une formulation granulée de grits de maïs contenant des conidies ou par injection d'une suspension de conidies. Toutes les plantes ont été infestées à l'aide de larves de la Pyrale du maïs,Ostrinia nubilalis, au stade V7 (cornet), V12 (fin de stade cornet), ou V17 (apparition de la panicule). Les plantes infestées au stade cornet et à la fin du stade cornet ont eu significativement plus de chenilles de Pyrale en train de miner que les plantes infestées au stade début de panicule mâle. Le pourcentage de plantes infestées parB. bassiana n'était pas significativement différent entre ces 3 stades phénologiques. Au fur et à mesure que les plantes se développaient,B. bassiana était isolé de différentes parties de la plante, la moelle étant plus souvent infestée que les ligules. Les applications foliaires deB. bassiana ont entraîné la destruction immédiate de la pyrale chez les plantes infestées au stade cornet. La baisse de l'efficacité deB. bassiana aux stades intermédiaires par comparaison avec son efficacité au moment de la récolte est discutée.
    Notes: Abstract The entomopathogenic fungus,Beauveria bassiana (Balsamo) Vuillemin, was applied to whorl-stage (V7) corn,Zea mays L., by foliar application of a granular formulation of corn grits containing conidia or by injection of a conidial suspension. All plants were infested with European corn borer larvae,Ostrinia nubilalis (Hübner), at the V7 (whorl), V12 (late-whorl), or V17 (pretassel) stage of plant development. Plants infested at whorl and late-whorl stages had significantly more European corn borer tunneling than did plants infested at the pretassel stage. The percentage of plants colonized byB. bassiana did not differ significantly among the whorl, late-whorl, and pretassel stages. As the plants matured,B. bassiana was isolated from different plant areas, with the pith more frequently colonized than the leaf collars. Foliar application ofB. bassiana provided immediate suppression ofO. nubilalis in those plants infested at whorl stage. The reduced efficacy ofB. bassiana at the intermediate plant stages relative to efficacy at harvest is discussed.
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