title: The role and interactions of cytosolic alkalization and hydrogen peroxide in ultraviolet B-induced stomatal closure in Arabidopsis.
abstract: Cytosolic alkalization has been shown to function as a key player in multiple stimuli-induced stomatal closure, but its role and relationship with hydrogen peroxide (H2O2) in ultraviolet B (UV-B)-induced stomatal closure remains unknown. In this paper, by stomatal bioassay and laser-scanning confocal microscopy, we observed that 0.5 W m(-2) UV-B induced cytosolic alkalization and H2O2 production in guard cells while inducing stomatal closure in Arabidopsis (Arabidopsis thaliana). Butyrate (a weak acid) reduced the cytosolic pH/H2O2 production and prevented stomatal closure by UV-B. Methylamine (a weak base) induced H2O2 production and stomatal closure while enhancing the cytosolic alkalization in guard cells under light alone. The rise in cytosolic pH of wild-type guard cells on exposure to UV-B was evident at 15 min and substantial at 45 min while H2O2 production started to largely increase after 60 min. The failure of UV-B-induced H2O2 production in AtrbohD/F guard cells did not affect the changes of guard cell pH during the first 60 min of UV-B radiation, but largely suppressed cytosolic alkalization after 60 min of UV-B radiation. These results indicate that cytosolic alkalization mediates UV-B-induced stomatal closure via activating H2O2 production and that H2O2 production can feedback-enhance cytosolic alkalization in Arabidopsis guard cells.
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Ge
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Mi-Mi
authors.initials: MM
authors.lastname: Wu
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China. Electronic address: hejm@snnu.edu.cn.
authors.forename: Jun-Min
authors.initials: JM
authors.lastname: He
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D020148:Butyric Acid / Q000494:pharmacology; D003600:Cytosol / Q000737:chemistry* / Q000187:drug effects / Q000528:radiation effects; D025461:Feedback, Physiological; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008744:Methylamines / Q000494:pharmacology; D059828:Plant Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D008744:Methylamines; D020148:Butyric Acid; D006861:Hydrogen Peroxide; C027451:methylamine
keywords: 2′,7′-bis-(2-carboxyethyl)-5,(6)-carboxyfluorescein acetoxymethyl ester; 2′,7′-dichlorofluorescin diacetate; ASA; Arabidopsis thaliana; BCECF-AM; Cytosolic alkalization; DPI; H(2)DCFDA; H(2)O(2); Hydrogen peroxide; MJ; Stomatal closure; UV-B; UV-B radiation; [Ca(2+)](cyt); ascorbic acid; cytosolic calcium concentration; cytosolic pH; diphenylene iodonium chloride; hydrogen peroxide; methyl jasmonate; pH(cyt); ultraviolet B