英文摘要

Accumulating evidence suggests that hydrogen sulfide (H2S) is a gaseous signaling molecule that regulates diverse cellular signaling pathways through persulfidation, which involves the post translational modification (PTM) of specific cysteine residues to form persulfides. However, the mechanisms that underlie this important redox-based PTM remain poorly understood in higher plants.

We have, therefore, analyzed how protein persulfidation acts as a specific and reversible signaling mechanism during the plant abscisic acid (ABA) response. Here we show that ABA stimulates the persulfidation of L-cysteine desulfhydrase 1 (DES1), an important endogenous H2S enzyme, at Cys44 and Cys205 in a redox-dependent manner. Moreover, sustainable H2S accumulation drives persulfidation of the NADPH oxidase respiratory burst oxidase homolog protein D (RBOHD) at Cys825 and Cys890, which enhance its ability to produce reactive oxygen species. Physiologically, S-persulfidation-induced RBOHD activity is relevant to ABA-induced stomatal closure.

Together, these processes form a negative feedback loop that fine-tunes guard cell redox homeostasis and ABA signaling. These findings not only expand our current knowledge of H2S function in the context of guard cell ABA signaling, but also demonstrate the presence of a rapid signal integration mechanism involving specific and reversible redox-based PTMs that occur in response to changing environmental conditions.