Hydrogen sulfide modulates plant hypoxic responses through the persulfidation of Plant Cysteine Oxidases

Hydrogen sulfide (H₂S) is a gaseous molecule historically regarded as toxic. Nevertheless, increasing evidence has brought to light important physiological roles in both animals and plants. In plants, H₂S is involved in environmental and developmental responses, such as stomatal closure and seed germination, and in tolerance mechanisms to different stress conditions like salinity, drought and waterlogging. In this study, we report a function of H₂S as a modulator of hypoxic responses in Arabidopsis thaliana. A combination of biochemical and genetic evidence demonstrates that H₂S inhibits the activity of Plant Cysteine Oxidases, the molecular sensors of oxygen, through protein persulfidation to modulate hypoxia-associated responses. Furthermore, we show that H₂S physiology contributes to responses to low oxygen, as disturbing H2S production impaired activation of hypoxia-responsive genes and submergence tolerance. Overall, this work introduces H₂S as signalling modulator in plant hypoxic responses and adds a regulatory layer to the plant oxygen-sensing mechanism.