Role of nitric oxide and hydrogen sulfide in plant aluminum tolerance

As gasotransmitter, nitric oxide (NO) and hydrogen sulfide (H2S) are involved in the regulation of plant tolerance to abiotic stresses. Aluminum (Al) toxicity triggers synthesis of NO and H2S and seriously affects plant growth and productivity. Exogenous NO and H2S alleviate Al toxicity in plants. However, the physiological and molecular mechanisms of NO and H2S in alleviating Al toxicity are very scattered. In this review, the advances in the effects of Al on the content of endogenous NO and H2S and the mechanisms of exogenous NO and H2S in alleviating Al toxicity in plants are summarized and discussed. The signaling pathway for the roles of NO and H2S in alleviating Al toxicity is also proposed.