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1

Electronic Resource

Differential display-mediated rapid identification of different members of a multigene family, HSP16.9 in wheat (1996)

Joshi, Chandrashekhar P. ; Nguyen, Henry T.

Springer

Plant molecular biology 31 (1996), S. 575-584

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ISSN: 1573-5028

Keywords: differential display ; heat shock proteins ; non-coding regions ; PCR ; reverse transcription ; wheat

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Isolation of cDNAs encoding individual members of a gene family is essential for assessing their role in a biological phenomenon. However, this process is often laborious and slow due to highly conserved protein-coding region that interferes with the isolation of the individual members. Identification of gene-specific probes from 3′ non-coding regions of different members can assist in the fast retrieval and characterization of individual members of a multigene family. We used the recent technique of differential display for the same purpose. As an example of a multigene family in plants, we selected a heat shock protein gene family, HSP16.9 from wheat, with estimated 12 members. We modified the original differential display technique for selective amplification of the 3′ non-coding regions of different wheat HSP16.9 genes by replacing the random 10-mer in the original method with a conserved HSP16.9 gene family-specific primer. Sixteen cDNA fragments from these experiments were sequenced and they represent 8 different members of a 12 member gene family. Our succes can be attributed to shorter 3′ non-coding regions that are typical of higher-plant genes and use of highly conserved gene family-specific primer in these experiments. This modified differential display technique can be of general application to other plant systems where cloning of the different members of a gene family is desired.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00042230

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Heat tolerance in spring wheat. I. Estimating cellular thermotolerance and its heritability (1998)

Fokar, M. ; Nguyen, Henry T. ; Blum, A.

Springer

Euphytica 104 (1998), S. 1-8

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ISSN: 1573-5060

Keywords: spring wheat ; heat tolerance ; heat stress

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract High temperature is a major environmental stress factor limiting wheat (Triticum aestivum L.) productivity. Improvement of heat tolerance in wheat is an important breeding objective. Genetic variation in cellular thermotolerance among 56 spring wheat cultivars was evaluated at the seedling stage of growth by cell membrane thermostability (CMS) and triphenyl tetrazolium chloride (TTC) assays. A subset of eight lines was also evaluated at the flowering stage using the same assays. With both assays Average thermotolerance tended to decrease from the seedling to the flowering stages. However, thermotolerance was well correlated between growth stages among the eight cultivars for both CMS (r = 0.92; p = 0.004) and TTC (r = 0.84; p = 0.050). The correlation between TTC and CMS among the eight cultivars tested at the seedling and the flowering growth stages was significant (r = 0.74; p = 0.031 and r = 0.75; p = 0.029, respectively). The same correlation was less strong, though still significant (r = 0.32; p = 0.014) across 56 cultivars at the seedling stage. In a study of the cross V747 (tolerant)/Barkaee (susceptible), broad sense heritability was estimated at 89% for TTC. Most of the genetic variance was additive. CMS in seedlings of 16 cultivars was positively and significantly (p ≤ 0.05) correlated with yields of these cultivars in each of four hot environments in Mexico, Sudan, India, and Brazil. The same correlations for TTC were positive but nonsignificant.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018346901363

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3

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Heat tolerance in spring wheat. II. Grain filling (1998)

Fokar, M. ; Blum, A. ; Nguyen, Henry T.

Springer

Euphytica 104 (1998), S. 9-15

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ISSN: 1573-5060

Keywords: spring wheat ; heat tolerance ; heat stress

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Heat stress during grain filling is a major constraint to wheat (Triticum aestivum L.) yield. This study was performed to evaluate the relationship between stem reserves as a constitutive trait and of thermotolerance to sustained wheat grain filling under heat stress. Significant variation was seen among cultivars in the reduction in grain weight per ear (RGW), kernel number, and single kernel weight under heat stress. Differences in RGW among cultivars were ascribed to variation in the reduction in both kernel number and kernel weight under heat stress. Variation in the potential capacity for using mobilized stem reserves among cultivars was ascribed to variations in both kernel number and kernel weight under defoliation and ear shading. There was a strong negative correlation across cultivars (r = − 0.96; p ≤ 0.01) between RGW and PSR. A significant positive correlation (r = 0.92; p ≤ 0.01) was found across cultivars between the rate of chlorophyll loss under heat stress and photosynthate stem reserves (PSR) indicating that a high potential capacity for utilizing stem reserves for grain filling may be linked with accelerated leaf senescence. There was a strong negative association across cultivars between RGW and cell membrane thermostability at seedling (r = − 0.98) and the flowering (r = − 0.92; p ≤ 0.01) growth stages. The results indicate that grain filling under heat stress is closely related to the capacity for stem reserve remobilization as a constitutive trait and to plant thermotolerance as expressed by CMS in heat-hardened seedlings or adult plants.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018322502271

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4

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Diversity among germplasm lines of the Ethiopian cereal tef [ Eragrostis tef (Zucc.) Trotter] (1999)

Assefa, Kebebew ; Ketema, Seyfu ; Tefera, Hailu ; [et al.]

Springer

Euphytica 106 (1999), S. 87-97

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ISSN: 1573-5060

Keywords: clustering ; diversity ; Eragrostis tef ; genetic advance ; germplasm ; heritability ; principal components ; tef

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Three hundred twenty germplasm lines of the major Ethiopian cereal, tef, [ Eragrostis tef (Zucc.) Trotter], were evaluated for 20 morphological, phenological and agronomic characters in two-replicated randomized complete blocks at Debre Zeit and Melkassa Agricultural Research Centers in Ethiopia during the 1995 main season. The objectives were to assess the diversity of the lines, and to estimate the broad sense heritability (H) and genetic advance (GA) of the various characters. The mean squares of genotypes were highly significant (p ≤ 0.001) for all the traits. The phenotypic and genotypic coefficients of variation ranged in that order from about 6–40% and 3–23% for days to maturity and grain yield/plant, and days to maturity and number of spikelets/main shoot panicle, respectively. The cluster analysis grouped the genotypes into 14 major complexes consisting of one to 183 lines. Of the 19 principal components involved in explaining the entire variation among the genotypes the first five which had eigenvalues of more than one explained about 73.8%. The first principal component which accounted for about 34% of the total variance was due chiefly to plant height, culm and panicle length, diameters of the two basal culm internodes, main shoot panicle mass and grain yield, number of main shoot panicle branches and spikelets, and days to panicle emergence and maturity. Estimates of H varied from about 22% for length of the lowest main shoot stem internode to 74% for number of main shoot panicle branches. Values of GA (expected from selection of the superior 5% of the lines and expressed relative to the means) ranged from about 3% for days to maturity to 36% for number of spikelets/main shoot panicle. Overall, the study indicated the existence of trait diversity in tef germplasm and this can be exploited in the genetic improvement of the crop through hybridization and selection.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1003582431039

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5

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Comparison of Measurement Methods of Osmotic Adjustment in Rice Cultivars (1999)

Babu, R. Chandra ; Pathan, M. Safiullah ; Blum, A. ; [et al.]

Springer

Crop science 39 (1999), S. 150-158

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: indica and japonica cultivars of rice (Oryza sativa L.) subjected to a drying cycle in large pots in the greenhouse. The four methods were: (i) derivation of OA from regressions of leaf relative water content (RWC) on leaf osmotic potential (OP); (ii) estimation of OA from OP of stressed plants calculated to rehydrated state; (iii) estimation of OA from OP of stressed plants that have been rehydrated; and (iv) estimation (from data used in Method 1) of OA capacity by the sustained RWC at a given OP of -3.5 MPa. Method 1 was a priori considered as the best estimate. Under relatively mild atmospheric conditions and a slow development of water deficit (first experiment), mean OA over 12 cultivars was 0.89, 0.51, and 0.72 Mpa by Methods 1, 2, and 3, respectively. Mean RWC at -3.5 Mpa was 69.3%. Significant (P ≤ 0.05) variation in OA among cultivars was observed by all methods, up to a four-fold difference in OA among cultivars (0.35-1.51 Mpa) by Method 1. Simple correlation for OA across 12 cultivars with Method 1 was significantly higher for Method 3 (r = 0.76; P = 0.04) and Method 4 (r = 0.87; P 〈 0.01) than for Method 2 (r = 0.54; P = 0.07). OA by Method 4 was better correlated with Method 3 (r = 0.80; P 〈 0.01) than with Method 2 (r = 0.67; P = 0.02). The coefficient of variation (CV) as a measure of error was greater for Method 1 (47%) and Method 2 (31%) than for Method 3 (21%) or 4 (24%). Both Methods 2 and 3 were less demanding on labor and plant materials than Methods 1 and 4. The results support the use of Method 3 (the "rehydration method") as a faster and an economical replacement for Method 1.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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6

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Amplified Fragment Length Polymorphism Analysis of Tef [Eragrostis tef (Zucc.) Trotter] (1999)

Bai, Giuhua ; Ayele, Mulu ; Tefera, Hailu ; [et al.]

Springer

Crop science 39 (1999), S. 819-824

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Eragrostis tef (Zucc) Trotter], is a major cereal crop in Ethiopia. The objective of this study was to investigate the genetic relationships among tef accessions by the amplified fragment length polymorphism (AFLP) technique. Forty-seven accessions of tef and one accession each of E. pilosa and E. curvula were analyzed. A total of 316 polymorphic DNA fragments across the three Eragrostis species were identified. The level of polymorphism within tef accessions was low (18%). However, with four or more primer pairs and a cluster analyses procedure, all the accessions included in the study were differentiated from each other. The three species studied fell in to three distinct clusters. Within tef, two major groups can be differentiated at 89% similarity. Because AFLP is reliable and enables assessment of potentially unlimited numbers of genetic loci, it permits greater insights into the genetic diversity of tef than had been possible with other available markers. Despite the low polymorphism level in tef, the availability of a large number of primer combinations and the high speed of the assay make AFLP an efficient marker technology for genetic diversity study of tef.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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7

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Genetic control of acquired high temperature tolerance in winter wheat (1995)

Porter, David R. ; Nguyen, Henry T. ; Burke, John J.

Springer

Euphytica 83 (1995), S. 153-157

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ISSN: 1573-5060

Keywords: acquired high temperature tolerance ; diallel analysis ; inheritance ; Triticum aestivum ; wheat

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary The development of high temperature-tolerant wheat (Triticum aestivum L.) germplasm is necessary to improve plant productivity under high-temperature stress environments. The quantification of high temperature tolerance and the characterization of its genetic control are necessary for germplasm enhancement efforts. This study was conducted to determine the genetic control of acquired high temperature tolerance in common bread wheat cultivars. Reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by heat-stressed seedling leaves was used as a quantitative measure to characterize acquired high temperature tolerance. Eleven-day-old seedlings of 20 F1 progeny produced through a complete 5×5 (‘Payne’, ‘Siouxland’, ‘Sturdy’, ‘TAM W-101’, and ‘TAM 108’) diallel mating design were acclimated at 37° C for 24 hours, followed by a 2-hour incubation at 50° C. Under these test conditions, acquired high temperature tolerance ranged from a high of 75.7% for the genotype TAM W-101 × TAM 108, to a low of 37.3% for the genotype Payne × Siouxland. Partitioning of genotypic variance revealed that only the general combining ability component effect was statistically highly significant, accounting for 67% of the total genotypic variation. These results suggest that enhancing the level of high temperature tolerance in wheat germplasm is feasible utilizing existing levels of genetic variability and exploiting additive genetic effects associated with high temperature tolerance.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01678043

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