Acclimation to drought stress generates oxidative stress tolerance in drought-resistant than -susceptible wheat cultivar under field conditions

Wheat crop may experience water deficit cycles during their life cycle, which induces oxidative stress. Present study was conducted to evaluate the role of oxidative stress management in the leaves of two wheat (Triticum aestivum L.) cultivars, C306 (drought-resistant) and Mod (drought-susceptible), when subjected directly to severe water stress (non-acclimated) or to water stress cycles of increasing intensity with an intermittent rewatering (drought-acclimation). Mild water stress during vegetative growth enabled C306 to acclimatize better than Mod during subsequent water stress of severe nature during post-anthesis period. The drought-acclimated C306 leaves maintained favourable water relations and lower membrane injury due to low H2O2, accumulation than non-acclimated C306 plants during severe water stress. This is due to systematic increase in the activity of H2O2 scavenging enzymes particularly APX and POX and maintenance of ascorbate and glutathione redox pool by efficient functioning of GR enzyme in the drought-acclimated C306 plants. In contrast, both acclimated as well as non-acclimated Moti plants exhibited loss in turgor potential, high H2O2 levels and poor antioxidant enzyme response leading to enhanced membrane damage during severe water stress conditions. Hence, present study shows that genotypic differences in drought tolerance could be, at least in part, attributed to the ability of wheat plants to acclimate and induce antioxidant defense under water deficit conditions. (c) 2006 Published by Elsevier B.V.