Hydrogen sulfide enhances rice tolerance to nickel through the prevention of chloroplast damage and the improvement of nitrogen metabolism under excessive nickel

Hydrogen sulfide (H2S) modulates plant tolerance to abiotic stresses, but its regulatory effects on nitrogen metabolism and chloroplast protection under nickel (Ni) stress in crop plants remain elusive. Taking this into account, we investigated the potential roles of sodium hydrosulfide (NaHS), a H2S generator, in the improvement of growth performance of rice plants under Ni stress. Results showed that NaHS successfully reversed the adverse effects of Ni, as reflected in plant growth and biomass, and photosynthesis attributes including photosynthetic rates, stomatal conductance, transpiration rate, internal CO2 concentration and photosynthetic pigment contents. NaHS generated H2S plays a crucial role in controlling the photosynthetic machinery of rice as evidenced by the ultrastructure of chloroplast viewed under transmission electron microscope (TEM). The reduced…