OsCBE1, a Substrate Receptor of Cullin4-Based E3 Ubiquitin Ligase, Functions as a Regulator of Abiotic Stress Response and Productivity in Rice

• Main Authors: Juyoung Choi, Wonkyung Lee, Gynheung An, Seong-Ryong Kim
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: International Journal of Molecular Sciences
• Subjects: abiotic stress; cullin4; crop productivity; E3 ubiquitin ligase; rice
• Online Access: https://www.mdpi.com/1422-0067/22/5/2487

Ubiquitination is an important environmental stress response, and E3 ubiquitin ligases play a major role in the process. T-DNA insertion mutants of rice, <i>Oscbe1-1</i>, and <i>Oscbe1-2,</i> were identified through the screening of cold stress tolerance at seedling stage. <i>O</i>s<i>cbe1</i> mutants showed a significantly higher cold stress tolerance in the fresh weight, chlorophyll content, and photosynthetic efficiency than wild type. Molecular prediction showed that <i>OsCBE1</i> (<i>Oryza sativa</i> Cullin4-Based E3 ubiquitin ligase1) encoded a novel substrate receptor of Cullin4-based E3 ubiquitin ligase complex (C4E3). Whereas <i>Oscbe1</i> mutants had fewer panicles and grains than wild type in the paddy field, the overexpression lines of <i>OsCBE1</i> had more panicles and grains, suggesting that <i>OsCBE1</i> is involved in the regulation of both abiotic stress response and development. <i>Oscbe1</i> mutants also showed ABA hypersensitivity during seed germination, suggesting <i>OsCBE1</i> function for the stress response via ABA signaling. In silico analysis of OsCBE1 activity predicted a CCCH-type transcription factor, OsC3H32, as a putative substrate. Co-IP (Co-immunoprecipitation) study showed that OsCBE1 interacts with OsDDB1, an expected binding component of OsCBE1 and OsC3H32. Additionally, expression of <i>OsOLE16, OsOLE18</i>, and <i>OsBURP5</i> were negatively related with expression of <i>OsCBE1</i>. These results suggest that <i>OsCBE1</i> functions as a regulator of the abiotic stress response via CCCH as a member of the C4E3.