SnRK2 protein kinases represent an ancient system in plants for adaptation to a terrestrial environment

First author: Akihisa Shinozawa; Affiliations: Tokyo University of Agriculture (东京农业大学): Tokyo, Japan

Corresponding author: Yoichi Sakata 

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 Physcomitrella patens from drought. Subclass III SnRK2s from both Arabidopsis and from the semiterrestrial alga Klebsormidium nitens, which contains all the components of ABA signalling except ABA receptors, complement Physcomitrella snrk2− 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SnRK2家族包括被子植物渗透胁迫和ABA响应的关键调控子，可分为三大亚类。当ABA非响应的第一类SnRK2在植物处于渗透胁迫下受到调控时，第三类的SnRK2在ABA响应中发挥作用。本文报道了一个基于古老的第三类SnRK2、ABA和一个上游类Raf激酶ARK共同组成的信号模块保护小立碗藓免受干旱的损害。来自拟南芥和半陆生藻类Klebsormidium nitens的第三类SnRK2均能够弥补小立碗藓snrk2−突变体，而拟南芥的第一类SnRK2则不能。其中，半陆生藻类Klebsormidium nitens中除了ABA受体，含有所有的ABA信号转导组分。作者假设最早的陆地植物发展出ABA、ARK和第三类SnRK2组成的信号转导模块，通过招募ABA调控一个预先存在的脱水响应，随后维管植物中演化出了一个新的第一类SnRK2系统赋予植物一个新的独立于之前老系统之外的渗透胁迫保护。

通讯：Yoichi Sakata (http://dbs.nodai.ac.jp/view?l=en&u=113)

个人简介：1992-1995年，北海道大学，博士。

doi: https://doi.org/10.1038/s42003-019-0281-1

Journal: Communications Biology

First Published: January 21, 2019