| Title | BRUTUS-LIKE1 (BTSL1) and BTSL2 repress abscisic acid responses during early seedling growth by targeting ABI5 for degradation |
| Author | Zhao, Junhui |
| Publication | PLANT JOURNAL |
| Year | 2026 |
| Volume | 125 |
| Issue | 6 |
| Corresponding Author | Liang, G |
| Abstract | Abscisic acid (ABA) signaling plays a critical role in plant growth and responses to abiotic stresses. The transcription factor ABA INSENSITIVE 5 (ABI5) is a key regulator of ABA signaling in Arabidopsis thaliana, and its protein homeostasis is essential for controlling seed germination and early seedling development. In this study, we identified BRUTUS-LIKE1 (BTSL1) and BTSL2, two RING-type E3 ubiquitin ligases, as essential regulators of ABA-inhibited cotyledon greening during early seedling development. Biochemical analyses revealed that BTSL1 and BTSL2 target ABI5 for ubiquitination and degradation. Genetic epistasis analysis demonstrated that ABI5 functions downstream of BTSL1/2, as the ABA-sensitive phenotype of btsl1 btsl2 mutants depends on ABI5. Consistently, loss-of-function mutations in BTSL1 and BTSL2 resulted in enhanced ABI5 activity in planta. Collectively, our findings uncover a regulatory mechanism by which BTSL1 and BTSL2 modulate early seedling growth by controlling ABI5 protein stability. |
