Exogenous hydrogen sulfide alleviates salt stress in wheat seedlings by decreasing Na+ content

Hydrogen sulfide (H2S) is an important gaseous molecule in a number of plant developmental processes and stress responses. Triticum aestivum L. (LM 15) is a salt-sensitive wheat cultivar that was used here to examine the effect of exogenous H2S on seedling growth, Na+ and K+ concentration, and Na+ transportation under NaCl stress. The results showed that pretreatment with 0.05 mM sodium hydrosulfide (NaHS), a H2S donor, for 12 h significantly alleviated the growth inhibition of wheat seedlings under 100 mM NaCl. In addition, pretreatment with NaHS decreased the Na+ concentration, Na+/K+ ratio, the selective absorption capacity for K+ over Na+ and Na+ efflux ratio, and increased the selective transport capacity for K+ over Na+ under salt stress. Additional experiments with CaCl2 (an inhibitor of nonselective cation channels-NSCCs), TEA(+) (an inhibitor of low affinity K+ transporter) or amiloride (an inhibitor of salt overly sensitive 1-SOS1) showed that NSCCs and SOS1 were the major pathways by which H2S reduced Na+ concentration in wheat seedlings. These results showed that exogenous H2S alleviated growth inhibition by maintaining a lower Na+ concentration in wheat seedlings under NaCl stress via the regulation of NSCCs and SOS1 pathways.