Exogenous Salicylic Acid Alleviates the Antimony (Sb) Toxicity in Rice (Oryza sativa L.) Seedlings

Abstract

Salicylic acid (SA) plays a crucial role in plant growth, development and stress resistance. However, little is known about the alleviatory role of SA against antimony (Sb) toxicity in plants. In this study, the morphological, cellular, and biochemical responses of rice (Oryza sativa L.) seedlings to exogenous SA under Sb stress were intensively investigated. According to the results, Sb stress resulted in a considerable growth inhibition in rice plants in terms of biomass and length of shoot and root, relative water content as well as chlorophyll content, all of which were significantly improved with application of exogenous SA. In addition, exogenous SA also significantly alleviated the oxidative damage induced by Sb, and lowered the content of malondialdehyde and hydrogen peroxide (H2O2) as well as free proline and total soluble sugar in the Sb-treated seedlings. Furthermore, our study proved that SA foliar application could reverse the detrimental effects of Sb both by decreasing the Sb uptake and stimulating the antioxidant enzymatic mechanism pathway. Taken together, our results confirmed that SA could protect rice plants from Sb-induced phytotoxic effects by restricting the accumulation of Sb, improving the performance of the photosynthesis system, regulating levels of osmoprotectants and modulating antioxidant defense mechanisms, therefore providing a theoretical basis for the exogenous utility of SA to counteract Sb stress in plants.