Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla, CA 92093-0116, USA.
Curr Biol. 2011 May 10;21(9):R346-55. doi: 10.1016/j.cub.2011.03.015.
The plant hormone abscisic acid (ABA) mediates seed dormancy, controls seedling development and triggers tolerance to abiotic stresses, including drought. Core ABA signaling components consist of a recently identified group of ABA receptor proteins of the PYRABACTIN RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family that act as negative regulators of members of the PROTEIN PHOSPHATASE 2C (PP2C) family. Inhibition of PP2C activity enables activation of SNF1-RELATED KINASE 2 (SnRK2) protein kinases, which target downstream components, including transcription factors, ion channels and NADPH oxidases. These and other components form a complex ABA signaling network. Here, an in depth analysis of the evolution of components in this ABA signaling network shows that (i) PYR/RCAR ABA receptor and ABF-type transcription factor families arose during land colonization of plants and are not found in algae and other species, (ii) ABA biosynthesis enzymes have evolved to plant- and fungal-specific forms, leading to different ABA synthesis pathways, (iii) existing stress signaling components, including PP2C phosphatases and SnRK kinases, were adapted for novel roles in this plant-specific network to respond to water limitation. In addition, evolutionarily conserved secondary structures in the PYR/RCAR ABA receptor family are visualized.
植物激素脱落酸（ABA）介导种子休眠，控制幼苗发育，并引发对非生物胁迫的耐受性，包括干旱。核心 ABA 信号成分包括最近鉴定的一组 ABA 受体蛋白，即吡咯并嘧啶抗性（PYR）/ABA 受体调节因子（RCAR）家族，它们作为蛋白磷酸酶 2C（PP2C）家族成员的负调节剂发挥作用。PP2C 活性的抑制使 SNF1 相关蛋白激酶 2（SnRK2）蛋白激酶得以激活，这些激酶靶向下游成分，包括转录因子、离子通道和 NADPH 氧化酶。这些和其他成分构成了一个复杂的 ABA 信号网络。在这里，对该 ABA 信号网络中成分的进化进行深入分析表明：（i）PYR/RCAR ABA 受体和 ABF 型转录因子家族在植物的陆地殖民化过程中出现，而在藻类和其他物种中不存在；（ii）ABA 生物合成酶已经进化为植物和真菌特异性形式，导致不同的 ABA 合成途径；（iii）现有的应激信号成分，包括 PP2C 磷酸酶和 SnRK 激酶，被适应于这个植物特异性网络中的新角色，以响应水分限制。此外，还可视化了 PYR/RCAR ABA 受体家族中进化保守的二级结构。
