title: Involvement of hydrogen peroxide and nitric oxide in salt resistance in the calluses from Populus euphratica.
abstract: Nitric oxide (NO) and hydrogen peroxide (H2O2) function as signalling molecules in plants under abiotic and biotic stresses. Calluses from Populus euphratica, which show salt tolerance, were used to study the interaction of NO and H2O2 in plant adaptation to salt resistance. The nitric oxide synthase (NOS) activity was identified in the calluses, and this activity was induced under 150 mM NaCl treatment. Under 150 mM NaCl treatment, the sodium (Na) percentage decreased, but the potassium (K) percentage and the K/Na ratio increased in P. euphratica calluses. Application of glucose/glucose oxidase (G/GO, a H2O2 donor) and sodium nitroprusside (SNP, a NO donor) revealed that both H2O2 and NO resulted in increased K/Na ratio in a concentration-dependent manner. Diphenylene iodonium (DPI, an NADPH oxidase inhibitor) counteracted H2O2 and NO effect by increasing the Na percentage, decreasing the K percentage and K/Na ratio. NG-monomethyl-L-Arg monoacetate (NMMA, an NO synthase inhibitor) and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxyde (PTIO, a specific NO scavenger) only reversed NO effect, but did not block H2O2 effect. The increased activity of plasma membrane (PM) H+ -ATPase caused by salt stress was reversed by treatment with DPI and NMMA. Exogenous H2O2 increased the activity of PM H+ -ATPase, but the effect could not be diminished by NMMA and PTIO. The NO-induced increase of PM H+ -ATPase can be reversed by NMMA and PTIO, but not by DPI. Western blot analysis demonstrated that NO and H2O2 stimulated the expression of PM H+ -ATPase in P. euphratica calluses. These results indicate that NO and H2O2 served as intermediate molecules in inducing salt resistance in the calluses from P. euphratica under slat stress by increasing the K/Na ratio, which was dependent on the increased PM H+ -ATPase activity.
authors.affiliation: Gansu Key Laboratory of Crop Genetic & Germplasm Enhancement, College of Life Sciences and Technology, Gansu Agricultural University, Lanzhou 730070, China. zhangf@gsau.edu.cn
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Yuping
authors.initials: Y
authors.lastname: Wang
authors.forename: Yingli
authors.initials: Y
authors.lastname: Yang
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.forename: Di
authors.initials: D
authors.lastname: Wang
authors.forename: Jianquan
authors.initials: J
authors.lastname: Liu
mesh_terms: D006861:Hydrogen Peroxide / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D032107:Populus / Q000187:drug effects* / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology*; D046509:Tissue Culture Techniques
chemical_list: D009569:Nitric Oxide; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D006180:Proton-Translocating ATPases