title: BRI1-Associated Receptor Kinase 1 Regulates Guard Cell ABA Signaling Mediated by Open Stomata 1 in Arabidopsis.
abstract: Stomatal movements are critical in regulating gas exchange for photosynthesis and water balance between plant tissues and the atmosphere. The plant hormone abscisic acid (ABA) plays key roles in regulating stomatal closure under various abiotic stresses. In this study, we revealed a novel role of BAK1 in guard cell ABA signaling. We found that the brassinosteroid (BR) signaling mutant bak1 lost more water than wild-type plants and showed ABA insensitivity in stomatal closure. ABA-induced OST1 expression and reactive oxygen species (ROS) production were also impaired in bak1. Unlike direct treatment with H2O2, overexpression of OST1 did not completely rescue the insensitivity of bak1 to ABA. We demonstrated that BAK1 forms a complex with OST1 near the plasma membrane and that the BAK1/OST1 complex is increased in response to ABA in planta. Brassinolide, the most active BR, exerted a negative effect on ABA-induced formation of the BAK1/OST1 complex and OST1 expression. Moreover, we found that BAK1 and ABI1 oppositely regulate OST1 phosphorylation in vitro, and that ABI1 interacts with BAK1 and inhibits the interaction of BAK1 and OST1. Taken together, our results suggest that BAK1 regulates ABA-induced stomatal closure in guard cells.
authors.affiliation: Department of Biological Sciences, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
authors.forename: Yun
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Department of Systems Biology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Changbo
authors.initials: C
authors.lastname: Dai
authors.affiliation: Department of Systems Biology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Myeong Min
authors.initials: MM
authors.lastname: Lee
authors.affiliation: Department of New Biology, Center for Plant Aging Research, Institute for Basic Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, Republic of Korea.
authors.forename: June M
authors.initials: JM
authors.lastname: Kwak
authors.affiliation: Department of Biological Sciences, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address: khnam514@sookmyung.ac.kr.
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000033:anatomy & histology / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D054046:Plant Stomata / Q000033:anatomy & histology / Q000187:drug effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013260:Steroids, Heterocyclic / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D017382:Reactive Oxygen Species; D013260:Steroids, Heterocyclic; D000040:Abscisic Acid; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; C108270:BRI1 protein, Arabidopsis; C023623:brassinolide
keywords: ABA-induced stomatal closure; Arabidopsis thaliana; BAK1; OST1