Unearthing The Alleviatory Mechanisms of Hydrogen Sulfide in Aluminum Toxicity in Rice

Abstract

Hydrogen sulfide (H2S) improves aluminum (Al) resistance in rice; however, the underlying molecular mechanism remains unclear. In the present study, treatment with 30-μM Al significantly inhibited rice root growth and increased the total Al content and apoplastic and cytoplasm Al concentration in the rice roots. However, pretreatment with NaHS (H2S donor) reversed these negative effects. Transcriptomics and physiological experiments confirmed that H2S increased the ATP, sucrose, glutathione, and ascorbic acid contents, which was accompanied by decreased O2·- and H2O2 contents, to alleviate Al toxicity. H2S significantly inhibited ethylene emissions in the rice and then inhibited pectin synthesis and increased the pectin methylation degree to reduce cell wall Al deposition. The phytohormones indole-3-acetic and brassinolide were also involved in the alleviation of Al toxicity by H2S. In addition, other pathways of material and energy metabolism, secondary metabolism, cell wall components, signal transduction, and transcriptional and translational pathways in the rice roots were also regulated by H2S under Al toxicity conditions. These findings improve our understanding of how H2S affects rice responses to Al toxicity, which will facilitate further studies on crop safety.