Study of heat stress memory related to acquired thermo-tolerance in wheat

Abstract

Wheat is one of the important plants frequently suffer by effects of heat stress. In the present study, heat priming for the first generation studied on heat tolerance of the successive generations in seedling and maturity stages under high temperature stress. Under high-temperature stress condition during seedling stage, the progeny of heat-primed (PH) genotypes shown significantly higher chlorophyll a and b content and percent tetrazolium chloride (%TTC) reduction than the progeny of the non-heat primed (NH) genotypes. At maturity stage, higher grain yield per plant was obtained for PH genotypes than NH genotypes under heat stress condition, which was mainly associated with the higher grain weight for PH than NH genotypes. The greater grain weight could be resulted from the higher percent cell membrane thermo-stability (%CMS) in the PH genotypes than in the NH genotypes. Estimation of variance components and broad sense heritability were higher in PH genotypes than observed in NH genotypes for most studied traits at seedling and maturity stages. Based on morpho-physiological traits, the highest genetic distance was recorded between G9 genotype of heat-primed plants and G9 genotype of non-primed plants, which gave highly significant differences between PH plants and NH plants for all studied traits. The heat priming for the parents may induce heat tolerance for offspring, and this might be an effective method to cope with severe heat stress during some the different growth stages in wheat.