Differential Gene Expression and Physiological Adaptation of Two Triticum aestivum Cultivars for Drought Acclimation

Document Type : Original Article

Authors

Science Department (biology section), Teachers college, King Saud University, Riyadh, KSA

Abstract

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.

Keywords