Pretreatment of seed with H2O2 enhances drought tolerance of wheat (Triticum aestivum L.) seedlings

Drought is an important environmental constraint limiting the productivity of many crops worldwide. Seedling tolerance to drought is crucial for crop growth and development through the whole season under water-limited condition. Experiments were conducted to investigate the effects of seed pretreatment by hydrogen peroxide (H2O2) on drought tolerance in wheat (Triticum aestivum L.) seedlings. H2O2-pretreated seeds exhibited 56% higher in germination rate than the water-pretreated seeds (control) under PGE-induced drought condition. Level of H2O2 in seedlings arising from H2O2-treated seeds grown under drought stress was markedly lower than the controls, indicating the operation of antioxidant system in them. These seedlings exhibited increased growth characteristics including higher net photosynthetic rate, leaf area and dry weight. Moreover, H2O2 treatment improved water use efficiency (WUE) and proline level. H2O2 pretreatment enhanced the membrane stability, as revealed from greatly reduced membrane damage rate (MDA) and malondialdehyde (MDA) content. The seedlings showed the higher expression of antioxidative enzyme such as catalase (CAT) and ascorbate peroxidase (APX). The present data suggest that H2O2, a stress signal, could trigger the activation of antioxidants in seeds, which persists in the seedlings to alleviate the oxidative damage, leading to improvements in physiological attributes for the seedling growth under drought.