BRI1-Associated Receptor Kinase 1 Regulates Guard Cell ABA Signaling Mediated by Open Stomata 1 in Arabidopsis

Yun Shang, Changbo Dai, Myeong Min Lee, June M. Kwak, Kyoung Hee Nam

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140 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)447-460
Number of pages14
JournalMolecular Plant
Issue number3
Publication statusPublished - 2016 Mar 7

Bibliographical note

Publisher Copyright:
© 2016 The Author.

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Plant Science


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