NaCl-induced alternations of cellular and tissue ion fluxes in roots of salt-resistant and salt-sensitive poplar species.
Using the scanning ion-selective electrode technique, fluxes of H+, Na+, and Cl- were investigated in roots and derived protoplasts of salt-tolerant Populus euphratica and salt-sensitive Populus popularis 35-44 (P. popularis). Compared to P. popularis, P. euphratica roots exhibited a higher capacity to extrude Na+ after a short-term exposure to 50 mM NaCl (24 h) and a long term in a saline environment of 100 mM NaCl (15 d). Root protoplasts, isolated from the long-term-stressed P. euphratica roots, had an enhanced Na+ efflux and a correspondingly increased H+ influx, especially at an acidic pH of 5.5. However, the NaCl-induced Na+/H+ exchange in root tissues and cells was inhibited by amiloride (a Na+/H+ antiporter inhibitor) or sodium orthovanadate (a plasma membrane H+-ATPase inhibitor). These results indicate that the Na+ extrusion in stressed P. euphratica roots is the result of an active Na+/H+ antiport across the plasma membrane. In comparison, the Na+/H+ antiport system in salt-stressed P. popularis roots was insufficient to exclude Na+ at both the tissue and cellular levels. Moreover, salt-treated P. euphratica roots retained a higher capacity for Cl- exclusion than P. popularis, especially during a long term in high salinity. The pattern of NaCl-induced fluxes of H+, Na+, and Cl- differs from that caused by isomotic mannitol in P. euphratica roots, suggesting that NaCl-induced alternations of root ion fluxes are mainly the result of ion-specific effects.
Sun
Jian
J
College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, People's Republic of China.
Chen
Shaoliang
S
Dai
Songxiang
S
Wang
Ruigang
R
Li
Niya
N
Shen
Xin
X
Zhou
Xiaoyang
X
Lu
Cunfu
C
Zheng
Xiaojiang
X
Hu
Zanmin
Z
Zhang
Zengkai
Z
Song
Jin
J
Xu
Yue
Y
D000584:Amiloride / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D006859:Hydrogen / Q000378:metabolism; D007477:Ions / Q000378:metabolism; D009997:Osmotic Pressure; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology*; D032107:Populus / Q000187:drug effects / Q000502:physiology*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000187:drug effects / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology
D007477:Ions; D017923:Sodium-Hydrogen Exchangers; D014638:Vanadates; D012965:Sodium Chloride; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D006180:Proton-Translocating ATPases