The CsBES1–14-CsCOR413 module mediated by brassinolide positively regulates cold resistance in tea plant

Abstract Camellia sinensis (L.) O. Kuntze exhibits severely restricted growth at low temperatures, resulting in reduced tea leaf yield and quality. BRI1-EMS-suppressor (BES) transcription factors, as key components of the brassinosteroids (BR) signaling pathway, are highly homologous to BZR and jointly regulate plants’ adaptation to environmental stress. In this study, the CsBES1–14 gene was successfully cloned and identified from the transcriptome database of tea plant. Biochemical analyses identified CsBES1–14 as a nuclear localized transcriptional activator, and BR and low temperature induced its expression. A. thaliana plants overexpressing CsBES1–14 exhibited increased chilling tolerance by promoting root growth and increasing the expression of cold responsive genes. Conversely, the suppression of CsBES1–14 through virus-induced gene silencing (VIGS) in tea plant notably impaired cold tolerance. Transcription Factor-centered Yeast One-Hybrid screening identified CsCOR413 as a downstream target, and electrophoretic mobility shift assays confirmed the direct binding of CsBES1–14 to specific cis-elements in the CsCOR413 promoter. Exogenous application of brassinazole (BRZ) and VIGS silencing experiments verified that the ICE-CBF cold response pathway could regulate the low temperature regulated protein CsCOR413. In summary, these findings elucidate that CsCOR413 expression is modulated not only by the classic ICE-CBF signaling pathway but also directly regulated by CsBES1–14. These findings outline the key components of the cold resistance network in tea plant and provide novel molecular targets for genetic improvement strategies in perennial crops.