Wheat heat response and genetic diversity revealed

Researchers evaluated 25 wheat genotypes for their response to high temperature and for genetic diversity during the 2020–21 Rabi season at two sites under timely and late sowing. Using the Heat Susceptibility Index (HSI), genotypes were classified as tolerant or susceptible, with some showing consistent behavior across sites and others differing by location. Four genotypes—HD2967, WH1142, HD3171 and WH1270—were reported as tolerant at both locations, while DBW71, K1317, WH1105 and HI1628 were consistently susceptible. Molecular marker analysis (SSR and STS) found similarity coefficients from 0.61 to 0.94, and clustering revealed four main genetic groups. The findings point to useful genetic variation for breeding programs focused on heat-related resilience.

What the study examined

This study looked at how 25 wheat varieties responded to heat during the 2020–21 Rabi season and how genetically diverse those varieties are. Plants were grown under timely and late sowing at two experimental sites, and their response to heat was assessed using the Heat Susceptibility Index (HSI). Genetic relationships among the varieties were explored using SSR and STS molecular markers.

Key findings

The HSI assessment grouped the varieties into tolerant and susceptible categories, and responses varied between locations for some genotypes. Four varieties—HD2967, WH1142, HD3171 and WH1270—were tolerant at both sites, while DBW71, K1317, WH1105 and HI1628 were susceptible at both locations. HD3086 was identified among the genotypes showing tolerance at both locations.

The molecular marker analysis showed genetic similarity values ranging from 0.61 to 0.94, with an average similarity of 0.77. Several genotype pairs reached the highest reported similarity index of 0.94. A cluster analysis produced a dendrogram with four major groups, each subdivided further.

Why it matters

Identifying which wheat genotypes hold up better under higher temperatures helps plant scientists and breeders understand which genetic material could be valuable for developing varieties suited to warmer conditions. The molecular diversity results highlight which genotypes are more closely related genetically and which offer distinct genetic variation. Together, the field responses and marker data provide a basis for selecting parent lines in breeding programs that aim to maintain yield and resilience under heat stress.