Hydrogen sulfide and rhizobia synergistically regulate nitrogen (N) assimilation and remobilization during N...

Hydrogen sulfide (H₂ S) is emerging as an important signalling molecule that regulates plant growth and abiotic stress responses. However, the roles of H₂ S in symbiotic nitrogen (N) assimilation and remobilization have not been characterized. Therefore, we examined how H₂ S influences the soybean (Glycine max)/rhizobia interaction in terms of symbiotic N fixation and mobilization during N deficiency-induced senescence. H₂ S enhanced biomass accumulation and delayed leaf senescence through effects on nodule numbers, leaf chlorophyll contents, leaf N resorption efficiency, and the N contents in different tissues. Moreover, grain numbers and yield were regulated by H₂ S and rhizobia, together with N accumulation in the organs, and N use efficiency. The synergistic effects of H₂ S and rhizobia were also demonstrated by effects on the enzyme activities, protein abundances, and gene expressions associated with N metabolism, and senescence-associated genes (SAGs) expression in soybeans grown under conditions of N deficiency. Taken together, these results show that H₂ S and rhizobia accelerate N assimilation and remobilization by regulation of the expression of SAGs during N deficiency-induced senescence. Thus, H₂ S enhances the vegetative and reproductive growth of soybean, presumably through interactions with rhizobia under conditions of N deficiency.