J Integr Plant Biol

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  • 收稿日期:2025-05-09 接受日期:2025-08-16

Phosphorylation-dependent activation of MAP4K1/2 by OST1 mediates ABA-induced stomatal closure in Arabidopsis

Dongxue Tang1, Dan Pei2, Meixiang Zhang3, Xiaoying Hu4, Minmin Lu1, Zhen Li1, Yu Wang1, Yi Wang1, Shuhua Yang1 and Zhizhong Gong1,4*   

  1. 1. State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
    2. Agronomy College, Henan Agricultural University, Zhengzhou 450046, China
    3. Key Laboratory of Medicinal Resources and Natural Pharmaceutical Chemistry of Ministry of Education, College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
    4. Institute of Life Science and Green Development, School of Life Sciences, Hebei University, Baoding 071001, China

    *Correspondence: Zhizhong Gong (gongzz@cau.edu.cn)
  • Received:2025-05-09 Accepted:2025-08-16
  • Supported by:
    This research was supported by grants from the National Science Foundation of China (31921001), and the Beijing Outstanding University Discipline.

Abstract: In higher plants, stomatal movements represent a critical physiological process that matains cellular water homestasis while enabling photosynthetic gas exchange. Open stomata 1 (OST1), a key protein kinase in the abscisic acid (ABA) signaling cascade, has been established as a central regulator of stomatal dynamics. This study reveals that two highly conserved mitogen-activated protein kinase 1 (MAP4K1) and MAP4K2 are positive regulators in ABA promoted stomatal closure, and ABA-activated OST1 potentiates MAP4K1/2 through phosphorylation at conserved serine and threonine residues (S166, T170, and S479/S488). The activated MAP4K1, in turn, phosphorylates two critical downstream targets: plasma membrane H+-ATPase 2 (AHA2) at residues T858, T881, and Y946, and slow anion channel-associated 1 (SLAC1) at T114 and S116. Functional analysis demonstrates that the phosphomimetic (3D: S166D/T170D/S479D) MAP4K1, but not non-phosphorylatable (3A: S166A/T170A/S479A) MAP4K1, could fully restore drought tolerance and reduced water loss in detached leaves of map4k1map4k2 double mutant. Our findings delineate a previously unrecognized signaling module comprising OST1–MAP4K1/2–AHA2/SLAC1, which crucially modulates ABA-mediated stomatal regulation. This work advances our mechanistic understanding of phosphorylation cascades governing plant water relations and stress responses.

Key words: AHA2,  MAP4K1/2, OST1, SLAC1, stomatal movements

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