Saini, Johar SinghSatinder Singh2021-08-202021-08-202021Satinder Singh (2021). Allelic diversity of alpha amylase genes in relation to heat stress tolerance in wheat (Triticum aestivum L.) (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810173039Wheat is one of the most important cereal cultivated across the world that forms the staple food of many communities in one way or another. Heat stresses associated with climate change scenarios and increased greenhouse gases, particularly CO2, delimit the genotypic potential of wheat cultivars. Alpha amylase is one of the key enzymes involved in starch metabolism at germination. Therefore, a panel of 96 wheat genotypes was screened for diversity of alpha amylase gene copies and response to heat stress under in vitro and in vivo conditions. In vitro screening based on germination percentage, coleoptile length, root length, coleoptile weight, root weight, speed of germination and seed vigour index 1 & 2 at different temperature treatments were used to scrutinize the genotypes for their stress tolerance. KSG1172, KSG0243 and KSG1214 were the best entries for seed vigour and thus show promise for early heat stress tolerance. SNP genotyping was used to construct a diversity based phylogenetic tree of the genotypes. The 96 genotypes were classified into three broad groups based on diversity in alpha amylase gene copies using UPGMA. Association analysis allowed identification of different gene copies under normal and heat stress conditions. Significant genotypic variations for germination, seedling vigour and yield characters under early, normal and late sown conditions were observed. Genotypes KSG0296 and KSG0025 were the best genotypes performing good in both early and late temperature stress as well as maintaining good germination percentage under elevated temperatures.EnglishThesis