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 (HS) is involved in multiple plant responses to toxic metal stress. Metal stress rapidly triggers endogenous HS production and exogenous HS alleviates metal toxicity in plants. To elucidate the role of HS in metal tolerance, the physiological and molecular mechanisms of HS in alleviating metal toxicity is necessary to be reviewed. Here, the latest progress on endogenous HS metabolism and the role of HS in plant responses to toxic metal stress were summarized and discussed. The mechanisms of exogenous HS in alleviating metal toxicity is proposed.