Evaluation of heat tolerance indices in bread wheat (Triticum aestivum L.) genotypes based on physiological, biochemical and molecular markers

Abstract

An experiment was carried out to examine wheat seed germination, vigor index, biochemical indices and genetic diversity associated with heat tolerance, using ISSR markers, under heat stress, viz., 22 ± 1, 25 ± 1, 30 ± 1 and 35 ± 1 °C referred as T0, T1, T2 and T3, respectively, in bread wheat genotypes. Wheat genotypes were categorized as heat tolerant and susceptible based on heat tolerance index (HTI). The germination percentage and seedling vigor index were positively correlated with HTI. The HTI was found higher in tolerant cv. GW-190, followed by GW-496, J-2010-02 and J-2010-10 genotypes under T3. Leaf proline content correlated positively with HTI. Sugars, free amino acids and protein content in leaf correlated positively with each other during heat stress. Total 24 ISSR primers were used to generate 124 bands across 10 wheat genotypes, of which 76 bands were polymorphic with an average of 3.16 bands per marker. The ISSR markers distinguished two clusters of wheat genotypes and out grouped heat tolerant genotype (GW-190 and GW-496) and heat sensitive genotype (J-2010-05) with minimum 68 % similarity. The jaccard similarity coefficient ranged from 0.68 to 0.89. The UBC-811 amplified unique markers distinguished tolerant GW-190 (152 bp) and sensitive J-2010-10 (110 bp) genotypes.