Abstract
Abscisic acid (ABA) plays a key role in many developmental processes and responses to adaptive stresses in plants. Recently, a new family of nucleocytoplasmic PYR/PYL/RCAR (PYLs) has been identified as bona fide ABA receptors. PYLs together with protein phosphatases type-2C (PP2Cs), Snf1 (Sucrose-non-fermentation 1)-related kinases subfamily 2 (SnRK2s) and downstream substrates constitute the core ABA signaling network. Generally, PP2Cs inactivate SnRK2s kinases by physical interaction and direct dephosphorylation. Upon ABA binding, PYLs change their conformations and then contact and inhibit PP2Cs, thus activating SnRK2s. Here, we reviewed the recent progress in research regarding the structures of the core signaling pathways of ABA, including the (+)-ABA, (−)-ABA and ABA analogs pyrabactin as well as 6AS perception by PYLs, SnRK2s mimicking PYLs in binding PP2Cs. PYLs inhibited PP2Cs in both the presence and absence of ABA and activated SnRK2s. The present review elucidates multiple ABA signal perception and transduction by PYLs, which might shed light on how to design small chemical compounds for improving plant performance in the future.
Highlights
ABSCISIC ACID Abscisic acid (ABA) was discovered half a century ago (Addicott and Lyon, 1969; Milborrow, 1974; Cutler et al, 2010)
The accumulating evidence indicate that PYLs function as bona fide ABA receptors, converging all aspects of ABA signaling
ABA perception by PYLs receptors is orchestrated by 2C-type protein phosphatase (PP2C) and SNF1-related protein kinase 2 (SnRK2) to establish a double-negative regulatory system for core ABA signaling, which controls ABA signaling in rapid stomatal closure responses for guard cells, as well as in long distance at the transcriptional level for seeds and vegetative tissues in response to water deficit
Summary
ABSCISIC ACID Abscisic acid (ABA) was discovered half a century ago (Addicott and Lyon, 1969; Milborrow, 1974; Cutler et al, 2010). Upon ABA binding, PYLs change their conformations and contact and inhibit PP2Cs, activating SnRK2s.
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