Hydrogen sulfide enhances salt tolerance through nitric oxide-mediated maintenance of ion homeostasis in barley seedling roots

Abstract

Hydrogen sulfide (H 2 S) and nitric oxide (NO) are emerging as messenger molecules involved in the modulation of plant physiological processes. Here, we investigated a signalling network involving H 2 S and NO in salt tolerance pathway of barley. NaHS, a donor of H 2 S, at a low concentration of either 50 or 100μM, had significant rescue effects on the 150mM NaCl-induced inhibition of plant growth and modulated the K + /Na + balance by decreasing the net K + efflux and increasing the gene expression of an inward-rectifying potassium channel (HvAKT1) and a high-affinity K + uptake system (HvHAK4). H 2 S and NO maintained the lower Na + content in the cytoplast by increasing the amount of PM H + -ATPase, the transcriptional levels of PM H + -ATPase (HvHA1) and Na + /H + antiporter (HvSOS1). H 2 S and NO modulated Na + compartmentation into the vacuoles with up-regulation of the transcriptional levels of vacuolar Na + /H + antiporter (HvVNHX2) and H + -ATPase subunit β (HvVHA-β) and increased in the protein expression of vacuolar Na + /H + antiporter (NHE1). H 2 S mimicked the effect of sodium nitroprusside (SNP) by increasing NO production, whereas the function was quenched with the addition of NO scavenger. These results indicated that H 2 S increased salt tolerance by maintaining ion homeostasis, which were mediated by the NO signal.