Evidence of association between specific heat-shock protein(s) and the drought and heat tolerance phenotype in maize

Abstract

Summary Although differences in heat-shock protein (HSP) patterns and differences in heritable drought and/or heat tolerance have been documented, there is no genetic evidence of association of the drought and/or heat tolerance with specific alterations in HSP expression in crop plants. In this study we tested the hypothesis that specific maize HSP(s) is(are) associated with plant ability to withstand soil drying (drought) and heat stress. We previously identified a line of maize, ZPBL 1304, which is tolerant to drought and heat stress and synthesizes a 45 ku (kDa) HSP(s), and a line of maize, ZPL 389, which is sensitive to drought and heat stress and does not synthesize the 45 ku HSP(s) (Ristic et al., 1991). We investigated possible association of the 45 ku HSP(s) of ZPBL 1304 line with the drought and heat tolerance phenotype. The two lines, ZPBL 1304 and ZPL 389, were crossed, and dehydration avoidance, damage to cellular membranes, and pattern of HSP synthesis were investigated in F2 plants after exposure to soil drying and high temperature (45°C) stress conditions. The 45 ku HSP(s) of ZPBL 1304 line was(were) associated with the drought and heat tolerance phenotype. The synthesis of 45 ku HSP(s) was observed in F2 plants that displayed an increased ability to recover from soil drying and heat stress. It is possible that either the 45 ku HSP(s) play a role in recovery from drought and heat stress or their gene(s) are in close proximity to the gene(s) which encode tolerance to drought and heat stress.