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Reactive oxygen species lead to cellular damage and in plants exposed to drought stress, an increasing expressions of genes encoding antioxidant enzymes play important protective roles. The aim of this study was to evaluate response of drought tolerant ('Arg' and 'Roshan') and drought sensitive ('Arta' and 'Navid') wheat cultivars to oxidative stress caused by drought. Relative water content (RWC), water loss rate (WLR), free proline content, malondialdehyde (MDA) accumulation, and peroxidase (POX) activity were measured after 2, 4, 6, and 8 h of dehydration. The tolerant cultivars had a higher RWC and lower MDA, proline content, POX activity and WLR as compared to the sensitive cultivars. Real-time quantitative PCR was used to measure the expressions of genes encoding antioxidant enzymes in chloroplastic thylakoids and stroma. The expressions of chloroplastic Cu/Zn superoxide dismutase, thylakoid-bound ascorbate peroxidase, mono-dehydroascorbate reductase, dehydroascorbate reductase, and chloroplastic glutathione reductase genes were up-regulated in the tolerant cultivars. A direct relationship between physiological traits and increased gene expressions was observed for both sensitive and tolerant cultivars. Overall, increasing gene expressions protect the plants from oxidative damage caused by dehydration stress and improves tolerance to this stress. |
