Acquisition of thermotolerance and HSP gene expression in durum wheat (Triticum durum Desf.) cultivars.

Plants are strongly affected by heat stress, which they overcome by modifying several physiological and biochemical mechanisms. At the cellular and molecular levels, the synthesis of heat shock proteins (HSPs) is essential in preventing or minimising the deleterious effect of high temperature. Plant responses to high temperatures are mediated by both their inherent ability to survive known as basal thermotolerance, and their ability to acquire thermotolerance after acclimation. A major aspect of the acclimation response involves the expression of HSP genes. Different Triticum durum cultivars were characterised for their response to high temperature at the physiological and molecular levels. Determination of cell membrane stability for both basal and acquired thermotolerance, and HSP gene expression analysis were performed. The two genotypes which contrasted most in their ability to acquire thermotolerance were exposed to different stress conditions and the expression of HSP101C and four small HSP genes was analysed. Differences in HSP transcripts accumulation were observed during the acclimation treatments. There is substantial evidence that induction of HSP gene expression has a role in the acquisition of thermotolerance; moreover, the accumulation of mitochondrial HSP transcripts appears to be related to the acquisition of thermotolerance.