The central role of hydrogen sulfide in plant responses to toxic metal stress

With the increase of industrial wastes, sewage irrigation, chemical fertilizers and pesticides, metal contamination is increasingly serious. How to reduce the environmental risk has become a compelling problem in cultivated land. As a gaseous signal molecule, hydrogen sulfide (H2S) is involved in multiple plant responses to toxic metal stress. Metal stress rapidly triggers endogenous H2S production and exogenous H2S alleviates metal toxicity in plants. To elucidate the role of H2S in metal tolerance, the physiological and molecular mechanisms of H2S in alleviating metal toxicity is necessary to be reviewed. Here, the latest progress on endogenous H2S metabolism and the role of H2S in plant responses to toxic metal stress were summarized and discussed. The mechanisms of exogenous H2S in alleviating metal toxicity is proposed.