title: Nitric oxide synthase-dependent nitric oxide production is associated with salt tolerance in Arabidopsis.
abstract: Nitric oxide (NO) has emerged as a key molecule involved in many physiological processes in plants. To characterize roles of NO in tolerance of Arabidopsis (Arabidopsis thaliana) to salt stress, effect of NaCl on Arabidopsis wild-type and mutant (Atnoa1) plants with an impaired in vivo NO synthase (NOS) activity and a reduced endogenous NO level was investigated. Atnoa1 mutant plants displayed a greater Na+ to K+ ratio in shoots than wild-type plants due to enhanced accumulation of Na+ and reduced accumulation of K+ when exposed to NaCl. Germination of Atnoa1 seeds was more sensitive to NaCl than that of wild-type seeds, and wild-type plants exhibited higher survival rates than Atnoa1 plants when grown under salt stress. Atnoa1 plants had higher levels of hydrogen peroxide than wild-type plants under both control and salt stress, suggesting that Atnoa1 is more vulnerable to salt and oxidative stress than wild-type plants. Treatments of wild-type plants with NOS inhibitor and NO scavenger reduced endogenous NO levels and enhanced NaCl-induced increase in Na+ to K+ ratio. Exposure of wild-type plants to NaCl inhibited NOS activity and reduced quantity of NOA1 protein, leading to a decrease in endogenous NO levels measured by NO-specific fluorescent probe. Treatment of Atnoa1 plants with NO donor sodium nitroprusside attenuated the NaCl-induced increase in Na+ to K+ ratio. Therefore, these findings provide direct evidence to support that disruption of NOS-dependent NO production is associated with salt tolerance in Arabidopsis.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Min-Gui
authors.initials: MG
authors.lastname: Zhao
authors.forename: Qiu-Ying
authors.initials: QY
authors.lastname: Tian
authors.forename: Wen-Hao
authors.initials: WH
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D018525:Germination; D008969:Molecular Sequence Data; D009154:Mutation; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D029681:Arabidopsis Proteins; D009569:Nitric Oxide; D012965:Sodium Chloride; D012964:Sodium; C521947:NOA1 protein, Arabidopsis; D019001:Nitric Oxide Synthase; D011188:Potassium