Exogenous salicylic acid and hydrogen peroxide attenuate drought stress in rice

Abstract

Hydrogen peroxide (H2O2) and salicylic acid (SA) exhibit protective effects against a wide array of stresses. In this study, we investigated the relative efficacy of exogenous H2O2 and SA in conferring drought tolerance in rice (Oryza sativa L.). The experiment was repeated two times, firstly in a hydroponic system and secondly in soil. The results revealed that drought hampered germination indices, seedling growth, photosynthetic pigments, and water content, whereas increased proline content. It also triggered higher H2O2 production and consequently elevated lipid peroxidation, which is a particular indication of oxidative damage. However, exogenous H2O2 or SA treatment effectively alleviated oxidative damage in rice seedlings both in hydroponic and soil systems via upregulating antioxidant enzymes. Nevertheless, regulation of proline level and augmentation of plant-water status were crucial to confer drought tolerance. Exogenous H2O2 or SA also protected photosynthetic pigments from oxidative damage that might help to maintain normal photosynthesis under drought. Besides, 5 mmol/L H2O2 and 0.5 or 1 mmol/L SA showed similar effectiveness on mitigating drought stress. Finally, our findings suggest that exogenous H2O2 or SA could evenly be effectual in the amending growth of rice seedlings under drought conditions.

Keywords

• abiotic stress tolerance
• phytohormone
• signaling molecule
• water stress