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An RGLG E3 Ubiquitin Ligase CaSIRE1 Negatively Regulates ABA-Dependent Drought Tolerance by Destabilizing CaSAP14 in
Hoyeol Choi1, Woonhee Baek1, Chae Woo Lim1
1Department of Life Science (BK21 Program), Chung-Ang University, Seoul, Korea.
Plant, Cell & Environment
|March 17, 2026
Summary
Pepper plants
Area of Science:
- Plant Biology
- Molecular Biology
- Stress Physiology
Background:
- Plants utilize the abscisic acid (ABA) signaling pathway for drought stress response.
- Post-translational modifications, particularly the ubiquitin-proteasome system, regulate ABA signaling by controlling protein turnover.
- E3 ligases are crucial in this system, determining substrate specificity and protein degradation.
Purpose of the Study:
- To identify and characterize novel regulators of drought stress and ABA signaling in pepper (Capsicum annuum).
- To elucidate the role of CaSIRE1 in modulating drought tolerance and ABA sensitivity.
- To investigate the molecular mechanism by which CaSIRE1 interacts with and regulates CaSAP14.
Main Methods:
- Gene silencing (RNA interference) in pepper plants.
- Gene overexpression in Arabidopsis thaliana.
- Yeast two-hybrid and Co-immunoprecipitation assays to confirm protein interactions.
- Ubiquitination assays and Western blotting to assess protein degradation.
- Phenotypic analysis under drought stress conditions.
Main Results:
- CaSIRE1, a RING-type E3 ligase, acts as a negative regulator of drought tolerance and ABA signaling in pepper.
- Silencing CaSIRE1 enhances drought tolerance and ABA sensitivity in pepper, while its overexpression in Arabidopsis reduces these traits.
- CaSIRE1 physically interacts with CaSAP14, promoting its ubiquitination and degradation via the 26S proteasome pathway.
- CaSIRE1-mediated degradation of CaSAP14 is reduced under drought stress, leading to increased CaSAP14 stability.
- CaSIRE1 functions upstream of CaSAP14 in the ABA signaling and drought stress response pathway.
Conclusions:
- A novel CaSIRE1-CaSAP14 regulatory module fine-tunes ABA-mediated drought stress response in pepper.
- This module dynamically modulates protein stability to adapt to drought conditions.
- CaSIRE1's role in CaSAP14 degradation is critical for regulating plant responses to water scarcity.
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