Sodium butyrate regulates the sulfur respiration of rhizosphere soil to produce hydrogen sulfide modulating histone acetylation dynamics to enhance drought tolerance in rice.

Hydrogen sulfide (H2S), a well-established gaseous signaling molecule, can effectively enhance plant tolerance to various environmental stresses. However, there is still a lack of suitable methods to release H2S in agricultural production, and the mechanism by which H2S improves stress resistance remains poorly understood. Here, we show the novel role of sodium butyrate (NaB) in producing H2S consistently in rice rhizosphere soil and the epigenetic mechanism of H2S to enhance rice drought tolerance. We found that NaB increased sulfate-reducing bacteria (SRB) abundance in the rhizosphere soil, resulting in higher expression of sulfite reductase (SiR), and consequently increased H2S production. Mechanistic investigation showed that H2S enhanced the level of H4K5ac in promoter regions of drought-tolerant genes, facilitating their expression by repressing the histone deacetylase (HDAC) gene OsHDA710. Loss-of-function mutants of OsHDA710 exhibited enhanced drought tolerance compared to wild-type (WT) plants, while OsHDA710 overexpression plants showed drought hypersensitivity. Moreover, we demonstrated that OsHDA710 could bind directly to promoters of drought-tolerance genes by recognizing the TGACC motif. Our findings illustrate an efficient way to produce H2S and a novel mechanism for H2S in improving the drought resistance of plants.