Desensitization of ABA-Signaling: The Swing From Activation to Degradation.

Akhtar Ali,Dae-Jin Yun,Jose M Pardo

doi:10.3389/fpls.2020.00379

Abstract

Abscisic acid (ABA) is a key plant stress-signaling hormone that accumulates upon osmotic stresses such as drought and high salinity. Several proteins have been identified that constitute the ABA-signaling pathway. Among them ABA receptors (PYR/PYL/RCAR), co-receptor PP2Cs (protein phosphatases), SnRK2 kinases (SNF1-related protein kinases) and ABI5/ABFs (transcription factors) are the major components. Upon ABA signal, PYR/PYL receptors interact with and recruit PP2Cs, releasing SnRK2s kinases from sequestration with PP2Cs. This allows SnKR2s to promote the activation of downstream transcription factors of ABA pathway. However, apart from activation, ubiquitination and degradation of core proteins in the ABA pathway by the ubiquitin proteasome system is less explored. In this review we will focus on the recent findings about feedback regulation of ABA signaling core proteins through degradation, which is emerging as a critical step that modulates and eventually ceases the signal relay. Additionally, we also discuss the importance of the recently identified effector protein HOS15, which negatively regulate ABA-signaling through degradation of OST1.

Highlights

Being sessile by nature, plants have evolved the ability to alter their physiology and development to adapt to the environmental challenges (Bohnert et al, 1995)
Several proteins were identified that work together to regulate abscisic acid (ABA) signaling including ABA-receptors and co-receptors, kinases and transcription factors (TFs) (Fujii et al, 2009; Fujita et al, 2009; Park et al, 2009; Brandt et al, 2012)
This review sheds light on the recent studies that focused on the degradation of ABA-signaling core components

Summary

INTRODUCTION

Plants have evolved the ability to alter their physiology and development to adapt to the environmental challenges (Bohnert et al, 1995). Unfavorable conditions, such as high salinity, cold or drought stress, are important challenges to agriculture as they reduce the yield potential of crop plants. Abscisic acid (ABA) is an important regulator of plant growth and development that plays a crucial role in both biotic and abiotic stress responses (Lee et al, 2006; Adie et al, 2007; Mang et al, 2012; Finkelstein, 2013). The phenotypes of the ABA-defective mutants (both in synthesis and/or signaling), which included loss of seed dormancy and early seedling growth and loss of stomatal movement, supported the importance of ABA in developmental and physiological responses (Koornneef et al, 1982; Lee et al, 2006; Finkelstein, 2013)

Desensitization of ABA Signaling Pathway

Target protein

CONCLUSION