title: Brassinosteroids modulate ABA-induced stomatal closure in Arabidopsis.
abstract: Stomatal movement in response to water availability is an important physiological process in the survival of land plants. The plant hormone abscisic acid (ABA) and brassinosteroids (BRs) regulate stomatal closure. The physiological functions of ABA and BRs, including germination, cell elongation and stomatal movement, are generally known to be antagonistic. Here, we investigated how BRs affect stomatal movement alone and in combination with ABA. We demonstrate that brassinoslide (BL), the most active BR, promotes stomatal closure in an ABA-independent manner. Interestingly, BL also inhibited ABA-induced stomatal closure when a high concentration of BL was added to ABA. Furthermore, we found that the induction of some genes for reactive oxygen species (ROS) generation by ABA (AtrbohD, NIA1 and NIA2) and subsequent ROS production were repressed by BL treatment. The BR signaling mutant bri1-301 failed to inhibit ABA-induced stomatal closure upon BL treatment. However, BRI1-overexpressing transgenic plants were hypersensitive to ABA during stomatal closure, and BL reversed ABA-induced stomatal closure more completely than in wild type plants. Taken together, these results suggest that BRs can positively and negatively modulate ABA-induced stomatal closure. Therefore, interactions between ABA and BR signaling are important for the regulation of stomatal closure.
authors.affiliation: Department of Biological Sciences, Sookmyung Women's University, Seoul 04310, Republic of Korea.
authors.forename: Yunmi
authors.initials: Y
authors.lastname: Ha
authors.affiliation: Department of Biological Sciences, Sookmyung Women's University, Seoul 04310, Republic of Korea.
authors.forename: Yun
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Department of Biological Sciences, Sookmyung Women's University, Seoul 04310, Republic of Korea khnam514@sookmyung.ac.kr.
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000502:physiology*; D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D060406:Brassinosteroids / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism / Q000502:physiology*; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D060406:Brassinosteroids; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D000040:Abscisic Acid
keywords: ABA sensitivity; ABA-induced stomatal closure; ROS production; abscisic acid (ABA); brassinosteroid (BR); stomatal movement.