Involvement of extracellular oxidative burst in salicylic acid-induced stomatal closure in Arabidopsis.
Salicylic acid (SA), a ubiquitous phenolic phytohormone, is involved in many plant physiological processes including stomatal movement. We analysed SA-induced stomatal closure, production of reactive oxygen species (ROS) and nitric oxide (NO), cytosolic calcium ion ([Ca²+](cyt)) oscillations and inward-rectifying potassium (K+(in)) channel activity in Arabidopsis. SA-induced stomatal closure was inhibited by pre-treatment with catalase (CAT) and superoxide dismutase (SOD), suggesting the involvement of extracellular ROS. A peroxidase inhibitor, SHAM (salicylhydroxamic acid) completely abolished SA-induced stomatal closure whereas neither an inhibitor of NADPH oxidase (DPI) nor atrbohD atrbohF mutation impairs SA-induced stomatal closures. 3,3'-Diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) stainings demonstrated that SA induced H₂O₂ and O₂⁻ production. Guard cell ROS accumulation was significantly increased by SA, but that ROS was suppressed by exogenous CAT, SOD and SHAM. NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) suppressed the SA-induced stomatal closure but did not suppress guard cell ROS accumulation whereas SHAM suppressed SA-induced NO production. SA failed to induce [Ca²+](cyt) oscillations in guard cells whereas K+(in) channel activity was suppressed by SA. These results indicate that SA induces stomatal closure accompanied with extracellular ROS production mediated by SHAM-sensitive peroxidase, intracellular ROS accumulation and K+(in) channel inactivation.
Graduate School of Natural Science and Technology, Okayama University, Tsushima-Naka, Okayama 700-8530, Japan.
Atiqur Rahman
AR
Khokon
Eiji
E
Okuma
Mohammad Anowar
MA
Hossain
Shintaro
S
Munemasa
Misugi
M
Uraji
Yoshimasa
Y
Nakamura
Izumi C
IC
Mori
Yoshiyuki
Y
Murata
D017360:Arabidopsis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D054046:Plant Stomata / Q000502:physiology*; D015221:Potassium Channels / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects*; D020156:Salicylic Acid / Q000494:pharmacology*; D015398:Signal Transduction
D015221:Potassium Channels; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D020156:Salicylic Acid; D002118:Calcium