A rice orthologue of the ABA receptor, OsPYL/RCAR5, is a positive regulator of the ABA signal transduction pathway in seed germination and early seedling growth

Abstract

Abscisic acid (ABA) is a phytohormone that positively regulates seed dormancy and stress tolerance. PYL/RCARs were identified an intracellular ABA receptors regulating ABA-dependent gene expression in Arabidopsis thaliana. However, their function in monocot species has not been characterized yet. Herein, it is demonstrated that PYL/RCAR orthologues in Oryza sativa function as a positive regulator of the ABA signal transduction pathway. Transgenic rice plants expressing OsPYL/RCAR5, a PYL/RCAR orthologue of rice, were found to be hypersensitive to ABA during seed germination and early seedling growth. A rice ABA signalling unit composed of OsPYL/RCAR5, OsPP2C30, SAPK2, and OREB1 for ABA-dependent gene regulation was further identified, via interaction assays and a transient gene expression assay. Thus, a core signalling unit for ABA-responsive gene expression modulating seed germination and early seedling growth in rice has been unravelled. This study provides substantial contributions toward understanding the ABA signal transduction pathway in rice.

A STRESS-RESPONSIVE NAC1-Regulated Protein Phosphatase Gene RiceProtein Phosphatase18Modulates Drought and Oxidative Stress Tolerance through Abscisic Acid-Independent Reactive Oxygen Species Scavenging in Rice

“…Similar ABA signaling components were also identified in rice (Kim et al, 2012). Most of the reported abiotic stress-related PP2Cs, such as ABI1, PP2CA, ZmPP2C, FsPP2C1, and FsPP2C2, mediate the stress responses through the regulation of ABA signaling pathways (Gosti et al, 1999;Tähtiharju and Palva, 2001;González-García et al, 2003;Reyes et al, 2006;Liu et al, 2009).…”

“…Here, we found that OsPP18, a typical PP2C, could not interact with SAPK2 ( Fig. 8A; a component of ABA signal transduction in rice identified by Kim et al [2012]) or other SAPKs in rice. Meanwhile, the expression of OsPP18 was not induced by ABA (Fig.…”

“…Recently, a core ABA signaling pathway composed of rice PYRABACTIN-RESISTANT MUTANT LIKE/ REGULATORY COMPONENTS OF ABA RECEPTOR5 (RCAR5), OsPP2C30, OSMOTIC STRESS/ABA-ACTIVATED PROTEIN KINASE2 (SAPK2), and RICE ABRE BINDING FACTOR for ABA-dependent gene regulation was identified in rice through interaction and transient gene expression assays (Kim et al, 2012). To determine whether OsPP18 is involved in ABA signaling, like OsPP2C30, pairwise interaction tests of OsPP18 with members of the rice SAPK family were conducted by using a yeast two-hybrid system (Fig.…”

“…To date, all of the reported PP2Cs, except ZmPP2C2 and FsPP2C1, were negative regulators of stress tolerance. The positive effect of ZmPP2C2 Kim et al [2012]), were analyzed in a yeast two-hybrid system. Cotransformed BDOsPP2C30 with AD-SAPK2 was used as a positive control.…”

Fundamental and applied research in ABA signaling: Regulation by ABA of the chromatin remodeling ATPase BRAHMA and biotechnological use of the PP2CA promoter.

“…Since the discovery of Arabidopsis PYR/PYL/RCAR receptors, several orthologous genes had been discovered in important crops as tomato, rice, strawberry and soybean (Sun et al, 2011, Chai et al, 2011, Kim et al, 2012, Bai et al, ! 28 2013.…”