Exogenous hydrogen sulphide alleviates nodule senescence in Glycine max-Sinorhizobium fredii symbiotic system

Abstract Aim Hydrogen sulphide (H 2 S), as a signaling molecule, modulate the process of plant growth and development. H 2 S is involved in the establishment of legume and rhizobia symbiosis relationship, but little is known about the role of H 2 S during nodule senescence. Method We study the function of H 2 S during nodule senescence in Glycine ma x- Sinorhizobium fredii symbiotic system. Physiological and biochemical method were conducted to modulate the nitrogen fixation, nodule structure, symbiotic and senescence related protein and gene expression. Results Our results indicated that exogenous H 2 S decreased the senesced nodules number, increased nitrogenease (Nase) activity, and promoted the accumulation of NO 3 - -N, NH 4 + -N, and total N, which caused the accumulation of biomass in the late steps of symbiosis. H 2 S alleviated nodule senescence by maintaining nodule normal nitrogen fixation structure. Meanwhile, the expression abundances of NifH and NodGS proteins were enhanced by H 2 S during nodule senescence. Moreover, H 2 S simulated the expression of symbiosis and nitrogen metabolism related genes in nodules. Finally, senescence related genes expression abundances were regulated by H 2 S during nodule senescence. Conclusion These findings suggested that H 2 S prolonged the lifespan of N 2 fixation by delaying nodule senescence and, which will be important to the increase of soybean yield and agricultural sustainability development.