Molecular genetic diversity analysis for heat tolerance of indigenous and exotic wheat genotypes

Four hundred and ninety-six indigenous and exotic aestivum and durum wheat accessions were phenotyped for heat tolerance at three locations during 2013–2014 and 2014–2015 crop seasons under very late sown conditions (35–40 °C). Promising 47 heat tolerant accessions, including 15 of durum were identified. Phenotypic data were recorded for quantitative traits and genotypic using molecular markers in these 47 lines. Polymorphism of 73.7% and 71.5% was detected using 137 and 109 SSR markers in aestivum and durum accessions respectively. In Triticum aestivum 308 alleles and in T. durum 234 alleles were detected with a range of 2–6. The genetic diversity ranged from 0.099 to 0.733 with average 0.488. Genotypes were classified into four categories based on their tolerance to stress as determined from Heat susceptibility index for grain yield. Dendrograms constructed using phenological, physiological and grain traits as well as molecular data were different with respect to alignment of genotypes indicating that genotypes differed genetically as well as physiologically in heat tolerance. Moreover phylogenetic tree is better choice as compared to population structure. The wheat breeders can pyramid these diverse sources to improve heat tolerance.