1Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagayaku, Tokyo, 156-8502 Japan.
2Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo,Sakura-ku, Saitama, 338-8570 Japan.
Commun Biol. 2019 Jan 21;2:30. doi: 10.1038/s42003-019-0281-1. eCollection 2019.
The SNF1-related protein kinase 2 (SnRK2) family includes key regulators of osmostress and abscisic acid (ABA) responses in angiosperms and can be classified into three subclasses. Subclass III SnRK2s act in the ABA response while ABA-nonresponsive subclass I SnRK2s are regulated through osmostress. Here we report that an ancient subclass III SnRK2-based signalling module including ABA and an upstream Raf-like kinase (ARK) exclusively protects the moss from drought. Subclass III SnRK2s from both Arabidopsis and from the semiterrestrial alga , which contains all the components of ABA signalling except ABA receptors, complement mutants, whereas Arabidopsis subclass I SnRK2 cannot. We propose that the earliest land plants developed the ABA/ARK/subclass III SnRK2 signalling module by recruiting ABA to regulate a pre-existing dehydration response and that subsequently a novel subclass I SnRK2 system evolved in vascular plants conferring osmostress protection independently from the ancient system.
SNF1 相关蛋白激酶 2（SnRK2）家族包括植物中与渗透胁迫和脱落酸（ABA）反应相关的关键调节剂，可分为三个亚类。第三亚类 SnRK2s 在 ABA 反应中起作用，而对 ABA 不敏感的第一亚类 SnRK2s 通过渗透胁迫调节。在这里，我们报告说，一个古老的基于第三亚类 SnRK2 的信号模块，包括 ABA 和一个上游的 Raf 样激酶（ARK），专门保护苔藓免受干旱。来自拟南芥和半陆生藻类的第三亚类 SnRK2，其中包含 ABA 信号的所有成分，除了 ABA 受体，能够互补突变体，而拟南芥的第一亚类 SnRK2 则不能。我们提出，最早的陆地植物通过招募 ABA 来调节预先存在的脱水反应，从而发展出 ABA/ARK/第三亚类 SnRK2 信号模块，随后在维管植物中进化出一种新的第一亚类 SnRK2 系统，该系统独立于古老的系统提供渗透胁迫保护。
