Mitigating Antimony Toxicity in Rice (Oryza Sativa L.) Through Exogenous Selenium Supplementation: A Comparative Study of Seed Priming, Hydroponics, and Foliar Spray Methods

Selenium (Se) has been used to counteract the stress of various metals (metaloids) in plants. However, the underlying mechanisms and comparative effects of different Se application methods on reducing toxicity and accumulation of metals have not been fully investigated. Antimony (Sb) is a toxic metalloid that seriously threatens to the health of plants, animals, and humans. In this study, the effects of three Se application methods, including seed priming, hydroponics and foliar spray, on the plant growth and physiological parameters, as well as Sb uptake and subcellular distribution and expression of stress-responsive genes were comprehensively investigated in rice seedlings (Oryza sativa L.) under Sb stress. The results demonstrated that Se application using the three methods could mitigate the negative effects of Sb on rice growth and photosynthesis, reduce oxidative stress levels, increase osmotic modulators, enhance enymatic and non enzymatic antioxidants, and restrict Sb uptake. Additionally, Se application could effectively alleviate the toxicity of Sb in rice seedlings by regulating Sb subcellular distribution and transcription levels of stress-related genes, including those in antioxidant system (OsCATA and OsCuZnSOD2), phytochelatin synthesis and transport (OsPCS2 and OsABCC1), cell wall modification (OsWAK11) and Se/Sb uptake (OsLsi1). Among the three different Se application methods, seed priming at low Se concentrations was apparently the most efficient, cost-effective and environmentally friendly strategy for alleviating the Sb toxicity in rice plants. Therefore, these findings contribute to our understanding of the alleviating mechanisms of Se against Sb in rice, providing a basis for further research to establish the best application method of exogenous Se.