A Novel Chemical Inhibitor of ABA Signaling Targets All ABA Receptors. Issue 4 (13th February 2017)

• Record Type: Journal Article
• Authors: Ye, Yajin; Zhou, Lijuan; Liu, Xue; Liu, Hao; Li, Deqiang; Cao, Minjie; Chen, Haifeng; Xu, Lin; Zhu, Jian-kang; Zhao, Yang
• Is Part Of: Plant physiology. Volume 173:Issue 4(2017)
• Page Start: 2356
• Page End: 2369
• Publication Date: 2017-02-13
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.01862
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Small molecule AA1 as a novel antagonist of ABA targets all ABA receptors of Arabidopsis. Abstract: Abscisic acid (ABA ), the most important stress-induced phytohormone, regulates seed dormancy, germination, plant senescence, and the abiotic stress response. ABA signaling is repressed by group A type 2C protein phosphatases (PP2Cs), and then ABA binds to its receptor of the ACTIN RESISTANCE1 (PYR1), PYR1-LIKE (PYL), and REGULATORY COMPONENTS OF ABA RECEPTORS (RCAR) family, which, in turn, inhibits PP2Cs and activates downstream ABA signaling. The agonist/antagonist of ABA receptors have the potential to reveal the ABA signaling machinery and to become lead compounds for agrochemicals; however, until now, no broad-spectrum antagonists of ABA receptors blocking all PYR/PYL-PP2C interactions have been identified. Here, using chemical genetics screenings, we identified ABA ANTAGONIST1 (AA1), the first broad-spectrum antagonist of ABA receptors in Arabidopsis ( Arabidopsis thaliana ). Physiological analyses revealed that AA1 is sufficiently active to block ABA signaling. AA1 interfered with all the PYR/PYL-HAB1 interactions, and the diminished PYR/PYL-HAB1 interactions, in turn, restored the activity of HAB1. AA1 binds to all 13 members. Molecular dockings, the non-AA1-bound PYL2 variant, and competitive binding assays demonstrated that AA1 enters into the ligand-binding pocket of PYL2. Using AA1, we tested the genetic relationships of ABA receptors with other core components of ABA signaling, demonstrating that AA1 is a powerful tool with which to sidestep this genetic redundancy of PYR/PYLs. In addition, the application of AA1 delays leaf senescence. Thus, our study developed an efficient broad-spectrum antagonist of ABA receptors and demonstrated that plant senescence can be chemically controlled through AA1, with a simple and easy-to-synthesize structure, allowing its availability and utility as a chemical probe synthesized in large quantities, indicating its potential application in agriculture.