Hydrogen sulfide promotes rice drought tolerance via reestablishing redox homeostasis and activation of ABA biosynthesis and signaling

Hydrogen sulfide (H2S) has been explored as the third biologically gasotransmitter regulating plant adaptation response, however, its possible mechanisms on drought tolerance are not completely clear yet. Here, we discovered that during dehydration treatment, the activities of L-cysteine desulfhydrase (LCD), the important synthetic enzymes of H2S in rice, was enhanced in rice seedling leaves, further leading to continuous increasing of endogenous H2S production. Pretreatment with NaHS, a well-known H2S donor, significantly improved rice performance under drought stress. The beneficial roles of NaHS were confirmed by the alleviation of lipid peroxidation, and the activation of antioxidant defence system. Importantly, besides repressing its degradation pathway, NaHS pretreatment promoted ABA de-novo synthesis as well. This resulted in an increase of ABA accumulation and the expression of downstream ABA-responsive genes in rice seedling upon drought stress. Together, the present study illustrated that H2S improve drought tolerance via reestablishing redox homeostasis and triggering ABA signaling.