Hydrogen sulfide mediates ion fluxes in root of poplars under NaCl stress

Using the non-invasive micro-test technique (NMT), the effects of exogenous NaHS (a H2 S donor) on ion fluxes in roots were investigated in a salt-tolerant species Populus euphratica and a salt-sensitive poplar spcies Populus popularis under the instantaneous salt stress (100 mmol·L-1 NaCl) and short-term salt stress (24 h, 50 mmol·L-1 NaCl). Both NaCl stress caused a K+ flux in roots of the poplar, and the salt-induced K+ flux was markedly inhibited by 50 μmol·L-1 NaHS. Moreover, the Na+ flux increment could be induced by NaHS under short-term salt stress, and also could be effectively inhibited by amiloride (a Na+ /H+ antiporter inhibitor) or sodium orthovanadate (a plasma membrane H+ -ATPase inhibitor). The results showed that the effects of H2 S on the inbition of K+ flux and the enhancement of Na+ /H+ antiport were more remarkably in the salt-sensitive P. popularis, compared to the salt-resistant P. euphratica. These concluded that the beneficial effects of H2 S were presumably due to the upward regulation of Na+ /H+ antiport system (H+ pump and Na+ /H+ antiporter), which drived the Na+ /H+ exchange across the PM, and simultaneously restricted the K+ flux through depolarization-ac- tivated channels.