Evolution of Abscisic Acid Signaling Module and Its Perception

Abstract

We hereby review the perception and responses to the stress hormone Abscisic acid (ABA), along the trajectory of 500M years of plant evolution, whose understanding may resolve how plants acquired this signaling pathway essential for the colonization of land. ABA levels rise in response to abiotic stresses, coordinating physiological and metabolic responses, helping plants survive stressful environments. In land plants, ABA signaling cascade leads to growth arrest and large-scale changes in transcript levels, required for coping with environmental stressors. This response is regulated by a PYRABACTIN RESISTANCE 1-like (PYL)-PROTEIN PHOSPHATASE 2C (PP2C)-SNF1-RELATED PROTEIN KINASE 2 (SnRK2) module, that initiates phosphor-activation of transcription factors and ion channels. The enzymatic portions of this module (phosphatase and kinase) are functionally conserved from streptophyte algae to angiosperms, whereas the regulatory component-the PYL receptors, putatively evolved in the common ancestor of Zygnematophyceae and embryophyte as a constitutive, ABA-independent protein, further evolving into a ligand-activated receptor at the embryophyta. This evolutionary process peaked with the appearance of the strictly ABA-dependent subfamily III stress-triggered angiosperms' dimeric PYL receptors. The emerging picture is that the ancestor of land plants and its predecessors synthesized ABA, as its biosynthetic pathway is conserved between ancestral and current day algae. Despite this ability, it was only the common ancestor of land plants which acquired the hormonal-modulation of PYL activity by ABA. This raises several questions regarding both ABA's function in ABA-non-responsive organisms, and the evolutionary aspects of the ABA signal transduction pathway.

Genome-Wide Identification and Characterization of Potato Long Non-coding RNAs Associated With Phytophthora infestans Resistance

“…The SAUR family may integrate various hormonal and environmental signals to regulate leaf senescence in Arabidopsis ( Wen et al, 2020 ). The PP2C-SnRK2-ABF signaling module plays an important role in the ABA signaling pathway ( Sun et al, 2020 ), which can promote plant defense to biotic and drought stresses by regulating stomatal opening and closure ( Lim et al, 2015 ). To investigate the potential regulatory mechanism of lncRNAs, we performed the transient expression assay in N. benthamiana using the lncRNA StLNC0004 with the highest expression level in the 11 lncRNAs from cluster 2 and found that StLNC0004 inhibited the colonization of P. infestans on N. benthamiana .…”

OsKEAP1 Interacts with OsABI5 and Its Downregulation Increases the Transcription of OsABI5 and the ABA Response Genes in Germinating Rice Seeds

“…In plants, ABA is the best-known stress signaling molecule, though its role as a growth signal is also essential in plant development and senescence. Over the past few decades, the core components of the ABA signaling pathway have been largely identified and characterized, though new genes are still being added (see reviews by Nonogaki [ 16 ], Hewage et al [ 35 ], and Sun et al [ 36 ]). Because OsKEAP1 and its orthologs are not part of the ABA signaling pathway in any of the working models proposed so far, no attempt has been made to link the KEAP1–NRF2 module to the ABA signaling module.…”

Exogenous Abscisic Acid Confers Salinity Tolerance in Chlamydomonas reinhardtii During Its Life Cycle

“…Some filamentous algae were recently found to express a transcript encoding an ortholog of the START domain PYRABACTIN RESISTANCE 1/PYR1‐LIKE/REGULATORY COMPONENTS OF ABA RECEPTOR (PYR/PYL/RCAR) proteins (Sun et al. 2019, 2020). However, since C. reinhardtii does not encode any PYR/L ABA receptor, it might possess other ABA‐binding protein that can mediate the response to ABA.…”