SSR marker analysis of thermotolerant and sensitive genotypes of wheat (Triticum aestivum L. em. Thell)
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Date
2010
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Publisher
CCSHAU
Abstract
Hexaploid bread wheat (Triticum aestivum L. em. Thell) is an important cereal food crop for
majority of world’s population. SSR markers show high level of polymorphism even in species with
narrow genetic base, such as wheat. High-temperature stress is one of the major constrains to wheat
production worldwide. This study was undertaken with the objective to assess polymorphism among
seven thermosensitive and seven thermotolerant genotypes of wheat. DNA extracted from young leaves
of 14 wheat genotypes was amplified by using 45 SSR primers. Out of these primers, 37 showed
amplification and were selected for further investigation. For SSR assays, data was analyzed to
calculate various parameters such as the number of total bands, number of polymorphic bands, per cent
polymorphism, bands per primer, polymorphic bands per primer, similarity matrices and dendrogram
construction. The polymorphism percentage ranger from 33.3% to100%, giving an average percentage
of polymorphism of 77.8%. The SSR primers yielded average 2.43 bands per primer. Overall size of
PCR amplified products ranged between 95bp and 1120bp. Based on SSR similarity matrix data, the
value of similarity coefficient ranged from 0.60 to 0.90 with an average genetic similarity of 0.76. At a
similarity coefficient 0.751, two group were formed which separated all thermotolerant and
thermosensitive genotypes in the dendrogram. Two and three dimensional PCA (Principle Component
Analysis) showed similar clustering as evident from cluster tree analysis. Primer Xgwm 46 showed a
≈200bp band which was present in all the thermotolerant genotypes and absent in all thermosensitive
genotypes. While WMC 170 produced three unique alleles of 215bp (WH 730 &WH 1021), 217bp
(GW 173 & NIAW 34) and 220bp (RAJ 3765 & WH 1076) which were present in all the
thermotolerant genotypes (except WH1022) but absent in all the thermosenstive genotypes. Xgwm46
and WMC 170 primers may probably be thermotolerance specific and may have potential for use in
marker assisted selection programs for wheat production improvement.
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Keywords
Vegetative propagation, Wheats, Planting, Genotypes, Developmental stages, Drying, Grain, Yields, Acidity, Biological development