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Author Spotlight: Advancing Stomatal Research with Automated Aperture Measurement
Published on: February 9, 2024
The RCAR12-CAP1-OST1 module controls ABA-mediated stomatal closure in Arabidopsis
Xiaoyi Li1, Qian Zhang1, Jiangjie Kang1
1Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China.
Abstract:
Phytohormone abscisic acid (ABA) induces the stomatal closure in plants under drought stress, a process requiring actin reorganization. Yet how ABA perception couples with cytoskeletal dynamics in stomatal closure remains unclear. In this study, we report that Arabidopsis cyclase-associated protein 1 (CAP1) functions as a negative regulator of ABA-induced drought responses through modulating actin network organization in Arabidopsis. Further analyses demonstrate that CAP1 interacts with RCAR12 suppresses actin filaments (F-actin) disassembly, whereas ABA disrupts the CAP1-RCAR12 interaction, thus recovering CAP1's depolymerization activity. Further, ABA-activated OST1 (OPEN STOMATA 1) phosphorylates CAP1 in Arabidopsis. OST1-mediated phosphorylation of CAP1 attenuates CAP1 binding to ADF4 and inhibits the ADF4-CAP1 complex. This inhibition leads to F-actin stabilization, which in turn maintains stomata in a closed state. This study demonstrates that CAP1 orchestrates ABA-induced stomatal closure under drought stress in Arabidopsis. Specifically, CAP1 acts by coupling ABA signaling to dynamic reorganization of actin cytoskeleton.
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