Differential Gene Expression and Physiological Adaptation of Two

Gene expression as a valuable stress marker in ecophysiological studies and rapid changes in gene expression in plants in response to stress are important for environmental adaptation. Two Triticum aestivum cultivars [drought sensitive (Sids-1) and drought tolerant (Veery)] were exposed to drought stress interrupted by rehydration period. The differentially expressed gene in drought stressed seedlings was strongly and rapidly induced in leaves of tolerant wheat (cvVeery) especially after rehydration, whereas induction was delayed and transcripts accumulated to a low level in sensitive one (cv Sids-1). Drought induced alteration in the expression of genes involved in signaling and in oxidative stress responses. A significant variability in drought tolerance was found between the two cultivars: while drought sensitive (Sids-1) oxidative stress indices were significantly increased after 4 days drought stress compared to the control, drought tolerant cultivar (Veery) indices increased after 8 days. After 2 days rehydration, plants exposed to 12 days drought showed better cultivar-dependent behavior, compared to those exposed to drought without rehydration and Veery cultivar showed better drought tolerance than Sids-1. This may be related to their antioxidant activity (smaller IC50 values for both 1,1-diphenyl-2- picrylhydrazyl and superoxide scavenging), associated with lower leaf MDA accumulation in comparison to sensitive cultivar. Taken together, results suggest that wheat may be interesting for production of antioxidant compounds, and that the cultivar-dependent capacity to induce antioxidative mechanisms in response to drought, may result in a corresponding variability for growth sustainability