Abscisic Acid Signaling in Plant Stress Responses and Tolerance

Abscisic acid (ABA) is a key phytohormone orchestrating plant adaptation to abiotic stresses such as drought, salinity and temperature extremes. Under stress conditions, ABA accumulates through enhanced biosynthesis and regulated transport, enabling its perception by PYR/RCAR receptors. Hormone binding to these receptors inhibits PP2C phosphatases, thereby activating SnRK2 kinases that phosphorylate downstream effectors to induce stomatal closure, osmoprotectant accumulation and stress‐responsive gene expression. The pathway is further modulated by ABA efflux transporters, calcium‐sensing modules and targeted protein degradation, creating feedback loops that tune signal intensity. Recent advances in structural biology, high‐throughput chemical screening and receptor engineering have clarified mechanisms of ligand recognition, transporter conformational changes and cross‐talk with calcium signalling. These insights underpin strategies for precision breeding and chemical priming aimed at enhancing crop resilience and securing agricultural productivity under changing climates.

Research from Nature Portfolio

Structural elucidation of the ABCG25 exporter has revealed the molecular basis of ABA efflux. Cryo-EM structures captured apo, ABA-bound and ATP-bound states, showing how hormone molecules dock within a transmembrane cavity and how ATP-driven conformational shifts facilitate their export. Functional assays confirmed key residues involved in binding and transport, linking transporter dynamics to stomatal regulation and seed germination. In parallel, studies of a calcium-sensing module composed of CBL1/9 calcineurin B-like proteins and the CIPK1 kinase have uncovered a negative regulatory circuit: under non-stress conditions, CIPK1 phosphorylates multiple PYL receptors, dampening ABA responsiveness. Drought-induced ABA accumulation blocks this phosphorylation, releasing the receptors to inhibit PP2Cs and activate downstream responses, thereby integrating calcium and ABA signals to optimise stress tolerance.

Abscisic Acid Signaling in Plant Stress Responses and Tolerance publication trend

The graph below shows the total number of articles in abscisic acid signaling in plant stress responses and tolerance across all publications each year (not limited to Nature Index journals).

Technical terms

Abscisic acid (ABA): A plant hormone central to stress signalling, regulating stomatal aperture, gene expression and osmolyte synthesis under adverse conditions.

PYR/RCAR receptors: Soluble ABA receptors that bind the hormone and inhibit type 2C protein phosphatases as an initial step in signal transduction.

PP2C phosphatases: A family of serine/threonine phosphatases that negatively regulate ABA signalling by dephosphorylating SnRK2 kinases in the absence of ABA.

SnRK2 kinases: Serine/threonine protein kinases activated upon ABA perception, initiating phosphorylation cascades that drive stress-responsive physiology.

ABCG25 transporter: An ATP-binding cassette exporter that mediates cellular efflux of ABA, shaping hormone distribution and signalling intensity.

CBL–CIPK module: A calcium-sensing network of calcineurin B-like proteins and CBL-interacting protein kinases that modulates ABA receptor activity in response to Ca²⁺ fluxes.

Receptor-agonist pair: A bioengineered combination of a modified receptor and synthetic ligand designed to activate ABA signalling with high specificity and conditional control.

References

1. Plant Hormone Transport and Localization: Signaling Molecules on the Move. Annual Review of Plant Biology (2023).
2. The CBL1/9-CIPK1 calcium sensor negatively regulates drought stress by phosphorylating the PYLs ABA receptor. Nature Communications (2023).
3. High‐Throughput Fluorescence Screening Enables Globally Consistent Identification of ABA Signaling Modulators. Advanced Science (2025).
4. Structure-guided engineering of a receptor-agonist pair for inducible activation of the ABA adaptive response to drought. Science Advances (2023).
5. Structural basis for abscisic acid efflux mediated by ABCG25 in Arabidopsis thaliana. Nature Plants (2023).