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Two hundred and seventy wheat varieties developed in India during the past 100 years were assessed for allelic diversity of waxy genes and two hundred varieties for starch pasting properties. Large variation was exhibited in starch pasting properties such as peak viscosity (159.3 to 303.2 RVU), RVA breakdown (28.5 RVU to 111.4 RVU), setback (73.2 to 116.3) and final viscosity (109.2 to 309.1 RVU) measured by Rapid Visco-Analyzer. Flour swelling power varied from 10.25 to 16.19 with the average value of 13.24. Final viscosity showed strong positive correlation with peak viscosity (R2 = 0.55). Significant positive correlation was observed between peak viscosity and flour swelling power (R2 = 0.37). Because flour swelling can be measured using 40 mg of the flour, it has utility in breeding programme to identify desirable recombinants in early segregating generations. Polymerase chain reaction (PCR) amplification of Wx-B1 locus showed the presence of Wx-B1 null in 60% of the varieties and exhibited significant positive correlation with peak viscosity (P < 0.01), flour swelling power (P < 0.001) and RVA breakdown (P < 0.001). Therefore, the combination of both the PCR for Wx-B1 null and microlevel test for starch properties such as FSP can be used for the improvement of flour properties suitable for various end-use products of wheat.

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Branlard, G., Dardever, M., Amiour, N., Igrejas, G. 2003. Allelic diversity of HMW and LMW glutenin subunits and omega-gliadin in French wheat ( Triticum aestivum L.). Genetic Resources and Crop Evolution 50 :669

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Seventy-three common winter wheat varieties developed throughout the breeding history of the DAI were investigated for their diversity of allelic variants on storage proteins component composition in grain. The high- and low molecular weight protein structures were determined by the widely used SDS-PAGE method of Payne et al. (1980). The ratio between the individual alleles on the loci of high and low molecular weight glutenin was analyzed. The change in the HMW-score was followed according to the period when the respective varieties were developed. The configuration Glu-A1 b , GluB1 c , Glu-D1 d , which was established in about 45% of the investigated genotypes, was most frequent in the high-molecular variants of glutenin. Concerning the low-molecular weight glutenins in 21 out of the 73 investigated varieties, the combination Glu-A3 c , Glu-B3 b , Glu-D3 c was observed; it coincided with the spectrum of the widely used variety Bezostaya 1. Highest diversity was established in the allelic variants of Glu-A3, Glu-B3 , in which 6 and 5 alleles, respectively, were observed. The quality of the varieties developed at DAI was relatively high (score 8.1). About a quarter of them are with high end-use quality confirmed in production. This is mainly due to the concentration of “strong” positive alleles in glutenin as a result from the intensive use of parents directly or indirectly related to Bezostaya 1, which lead to decrease of the percent of Glu-B1a (2 + 12). Quality should be further increased by additional diversity of combinations between “possitive” as effect on end-use grain quality alleles. Concerning HMW loci to keep of high grain end-use quality, it is necessary to maintain the status of Glu-A1b (2*), as well as of Glu-D1d (5 + 10).

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Two hundred and forty diverse set of wheat cultivars released in India during the last several decades were evaluated for HMW and LMW glutenin alleles, for assessing their diversity and effect on sedimentation volume and mixograph parameters. Both SDS-PAGE and PCR based markers were employed in identifying alleles encoded at Glu-1 and Glu-3 loci. Extensive allelic variation was observed at both the Glu-1 and Glu-3 loci. There was prevalence of Glu-A1b, Glu-B1i, Glu-D1a, Glu-A3c, Glu-B3b, Glu-B3g and Glu-D3b. The alleles Glu-A1b, Glu-B1i, Glu-D1d, Glu-A3b, Glu-B3g/h and Glu-D3b exhibited high SDS-sedimentation volume. Glu-B1i and Glu-D1d showed highly significant positive effect (p < 0.001) on sedimentation volume and also had additive effects. However, surprisingly overall there was decline in the frequency of Glu-B1i allele during last two decades in Indian wheat breeding and not a single 1B/1R translocation cultivar possessed this allele. Glu-A1b showed significant positive effect on mixograph peak time, peak slope and peak width. Glu-B3g exhibited significantly higher mixograph peak time and width at 8 and Glu-B3h showed higher dough stability. Glu-B3j (1B/1R translocation) exhibited highest peak slope indicating the negative effect on dough strength. This information can be useful in designing breeding program for the improvement of Indian bread wheat quality.

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This study was undertaken to investigate the allelic diversity in seed storage proteins in 11 substituted hexaploid triticale cultivars (all spring). These cultivars were developed at the Cereal Institute of Thessaloniki, Hellas, in the 1970s and 1980s, after selection on segregating material originating from International Maize and Wheat Improvement Center (CIMMYT). Seeds from each line were used to determine alleles at the loci for high molecular weight glutenin subunits (HMW-GS) Glu-A1, Glu-B1, Glu-R1 (or Sec-3 ) and gliadins (the loci Gli-A1 and Gli-B1 ). For this to be done, acid polyacrylamide gel electrophoresis for gliadins and SDS-electrophoresis for high molecular weight glutenins (HMW-GS) were applied. Analysis of the electrophoretic patterns obtained from the above-mentioned material revealed that only 5 out of the 11 cultivars were biochemically uniform (cv. ‘Vryto’, ‘Thisvi’, ‘Dada’, ‘Leto’ and ‘Ekate’). On the contrary, the rest of the cultivars, despite they were under seed production process, exhibited heterogeneity. Cv. ‘Dada’, which was found to be uniform, is of special interest, due to its productivity, especially under drought stress conditions.

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Glutenin and gliadin subunits play a key role in flour processing quality by network formation in dough. Wild relatives of crops have served as a pool of genetic variation for decades. In this study, 180 accessions from 12 domesticated and wild relatives of wheat were characterized for the glutenin and gliadin genes with allele-specific molecular markers. A total of 24 alleles were detected for the Glu-A3 and Gli-2A loci, which out of 19 amplified products identified as new alleles. Analysis of molecular variance (AMOVA) indicated that 90 and 65% of the genetic diversity were partitioned within two Aegilops and Triticum genera and their species, respectively. Furthermore, all glutenin and gliadin analyzed loci were polymorphic, indicating large genetic diversity within and between the wild species. Our results revealed that allelic variation of Glu-3A and Gli-As.2 is linked to genomic constitutions so that, Ae. caudata (C genome), Ae. neglecta (UM genome), Ae. umbellulata (U genome) and T. urartu (Au genome) harbor wide variation in the studied subunits. Hence, these species can be used in wheat quality breeding programs.

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Allele composition of 12 Hellenic commercial cultivars and 17 local populations of durum wheat was evaluated at the gliadin (Gli-A1, Gli-B1, Gli-A2, Gli-B2) and high-molecular-weight glutenin subunit loci (Glu-A1, Glu-B1). Acid polyacrylamide gel electrophoresis (APAGE) for gliadins and SDS-electrophoresis for HMW-GS were applied. Electrophoretic analysis revealed that five of the examined local populations, which are registered as durum wheat, are actually bread wheat. The predominant alleles in both the groups of Hellenic durum wheats are Gli-A1r, Gli-B1h, Glu-A1c, Gli-B2-1. At the Glu-B1 locus the allele Glu-B1b associated with better quality predominates among the cultivars (58%), whereas the allele Glu-B1e (50%) shows the highest frequency among the local populations. Only three samples, two cultivars (Syros and Lemnos) and one local population (Local of Heraklio), carry the gene locus Gli-B1 component γ42, which is an index of inferior end product quality. Higher genetic diversity at the studied storage protein loci of the homoeologous group 1 chromosomes (Glu-A1, Glu-B1, Gli-A1, Gli-B1) was recorded in the local Hellenic populations of durum wheat compared to the group of the Hellenic commercial cultivars. The results suggest their potential for widening the gene pool of commercial durum wheat cultivars.

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Branlard, G., Dardevet, M., Amiour, N., Igrejas, G. 2003. Allelic diversity ofHMWandLMWglutenin subunits and omega-gliadins in French bread wheat ( Triticum aestivum L.). Genetic Res. and Crop Evol. 50 :669

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The allelic variation for Glu-1, Glu-3 loci and presence of IBL-1RS translocation was determined in 126 spring wheat accessions. The most common alleles at Glu-1 loci were Glu-A1b (59.52%), Glu-B1c (41.26%), and Glu-D1d (57.14%) and at Glu-3 loci were Glu-A3c (56.45%), Glu-B3j (29.36%), and Glu-D3b (76.98%). Modern Pakistani wheat varieties carried superior alleles at Glu-1 and Glu-3 loci for bread-making quality and had no negative influence of secalin protein-synthesized by 1BL-1RS translocation. For LMW-GS, the most common combination was Glu-A3c, Glu-B3j and Glu-D3b. The loci Glu-B1 and Glu-B3 had the highest allelic diversity of Glu-1 and Glu-3 loci, respectively.

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Vernalization and photoperiod response genes play a significant role in the geographical adaptation, agronomic performance and yield potential of crops. Therefore, understanding the distribution pattern and allelic diversity for vernalization and photoperiod genes are important in any wheat breeding program. In this study, we screened 63 bread wheat cultivars and 7 bread wheat landraces from Turkey for photoperiod (Ppd-D1) and vernalization genes (Vrn-A1, Vrn-B1, Vrn-D1 and Vrn-B3) using diagnostic molecular markers. The photoperiod insensitive dominant allele, Ppd-D1a, was present in 60% of wheat cultivars and 42% of landraces, whereas, all other genotypes carried the photoperiod sensitive allele Ppd-D1b as recessive allele. Twenty-four cultivars and two landraces contained recessive alleles for all four VRN loci, whereas 39 wheat cultivars and 6 landraces contained one or more dominant VRN alleles. The highest percentage of Turkish wheat cultivars contained the dominant Vrn-B1 allele followed by Vrn-D1 and Vrn-A1. Information for vernalization and photoperiod alleles in Turkish germplasm will facilitate the planning and implementation of molecular markers in wheat breeding programs. This information will be helpful to develop elite wheat cultivars carrying suitable vernalization and photoperiod alleles with higher grain yield potential and better quality suitable for different production environments through marker assisted selection.

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