Updates on the Role of ABSCISIC ACID INSENSITIVE 5 (ABI5) and ABSCISIC ACID-RESPONSIVE ELEMENT BINDING FACTORs (ABFs) in ABA Signaling in Different Developmental Stages in Plants.

Anna Collin,Iwona Szarejko,Agata Daszkowska-Golec

doi:10.3390/cells10081996

Anna Collin, Iwona Szarejko + Show 1 more

Open Access

https://doi.org/10.3390/cells10081996

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Journal: Cells	Publication Date: Aug 5, 2021
Citations: 51	License type: CC BY 4.0

Affiliation: University of Silesia

Abstract

The core abscisic acid (ABA) signaling pathway consists of receptors, phosphatases, kinases and transcription factors, among them ABA INSENSITIVE 5 (ABI5) and ABRE BINDING FACTORs/ABRE-BINDING PROTEINs (ABFs/AREBs), which belong to the BASIC LEUCINE ZIPPER (bZIP) family and control expression of stress-responsive genes. ABI5 is mostly active in seeds and prevents germination and post-germinative growth under unfavorable conditions. The activity of ABI5 is controlled at transcriptional and protein levels, depending on numerous regulators, including components of other phytohormonal pathways. ABFs/AREBs act redundantly in regulating genes that control physiological processes in response to stress during vegetative growth. In this review, we focus on recent reports regarding ABI5 and ABFs/AREBs functions during abiotic stress responses, which seem to be partially overlapping and not restricted to one developmental stage in Arabidopsis and other species. Moreover, we point out that ABI5 and ABFs/AREBs play a crucial role in the core ABA pathway’s feedback regulation. In this review, we also discuss increased stress tolerance of transgenic plants overexpressing genes encoding ABA-dependent bZIPs. Taken together, we show that ABI5 and ABFs/AREBs are crucial ABA-dependent transcription factors regulating processes essential for plant adaptation to stress at different developmental stages.

Highlights

The core abscisic acid (ABA) signaling consists of ABA receptors (PYRABACTIN RESISTANCE PROTEINS/PYR-LIKE PROTEINS/REGULATORY COMPONENTS OF ABA RECEPTOR; PYR/PYL/RCAR), phosphatases (PHOSPHATASE 2Cs; PP2Cs), kinases (SNF1-RELATED PROTEIN KINASE 2; SnRK2s), and transcription factors belonging to large BASIC LEUCINE ZIPPER family
ABA-dependent BASIC LEUCINE ZIPPER (bZIP), ABA INSENSITIVE 5 (ABI5) and ABFs/AREBs are a group of transcription factors that trigger plant adaptation to unfavorable stress conditions
Their activity is strictly controlled by multiple regulators at transcriptional and protein level to ensure the accurate response to surrounding environmental conditions

Summary

Insight into the Core ABA Signaling and ABA-Dependent bZIPs Function

Each year abiotic stresses, including drought and salinity, reduce crop yield, causing economic problems and a severe threat to food safety. After perceiving the primary stress signal, ABA forms a complex with PYR/PYL/RCAR receptors and PP2C phosphatases It prevents PP2Cs from dephosphorylating SnRK2s and releases a SnRK2s phosphorylation activity. Phosphorylated ABI5 and ABFs/AREBs recognize ABA RESPONSIVE ELEMENTs (ABRE cis-elements) containing (C/T)ACGTGGC motif and G-box coupling elements (GCEs) with ACGT/C core sequence, present in the promoters of stressresponsive genes. These bZIP factors activate or repress their expression and trigger plant adaptation to stress [5,14,15]. We focus on ABI5 and ABFs/AREBs actions in the feedback regulation of ABA pathway and the possibility of utilizing ABA-dependent bZIPs in developing stress-tolerant cultivars

New Evidence of ABI5 Regulatory Role during Seed Germination

Involvement of ABI5 in Phytohormonal Crosstalk at the Seed Germination Stage

The Function and Regulation of ABI5 during Seedling Development

10. Stress Tolerance of Transgenic Plants Overexpressing ABA-Dependent bZIPs

11. Concluding Remarks