title: NaCl-induced alternations of cellular and tissue ion fluxes in roots of salt-resistant and salt-sensitive poplar species.
abstract: 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.
authors.affiliation: College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Shaoliang
authors.initials: S
authors.lastname: Chen
authors.forename: Songxiang
authors.initials: S
authors.lastname: Dai
authors.forename: Ruigang
authors.initials: R
authors.lastname: Wang
authors.forename: Niya
authors.initials: N
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Shen
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Zhou
authors.forename: Cunfu
authors.initials: C
authors.lastname: Lu
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Zheng
authors.forename: Zanmin
authors.initials: Z
authors.lastname: Hu
authors.forename: Zengkai
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Song
authors.forename: Yue
authors.initials: Y
authors.lastname: Xu
mesh_terms: 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
chemical_list: D007477:Ions; D017923:Sodium-Hydrogen Exchangers; D014638:Vanadates; D012965:Sodium Chloride; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D006180:Proton-Translocating ATPases