Cold snaps can restrict tea growth, damage young leaves, and reduce crop yield and quality, yet the molecular links between hormone signaling and cold defense have remained unclear. A new study identifies a brassinosteroid-responsive regulatory module that helps tea plants withstand low temperatures. The BRI1-EMS-Suppressor 1 (BES1) family transcription factor CsBES1-14 directly activates the cold-regulated protein CsCOR413, strengthening membrane stability, antioxidant capacity, and expression of cold-response genes. The findings connect brassinosteroid signaling with the established cold-defense network and identify two molecular targets that could support the development of more cold-resilient tea cultivars and potentially improve stress tolerance in other perennial crops exposed to chilling or freezing conditions. This molecular relay provides a clearer route from basic discovery to crop improvement.
Tea plants ( Camellia sinensis ) are adapted to warm environments and can suffer severe cellular injury during prolonged chilling or freezing. Plants respond by stabilizing membranes, adjusting osmotic balance, removing reactive oxygen species, and activating cold-responsive genes. Brassinosteroid (BR) signaling regulates plant growth and environmental adaptation, while the inducer of C-repeat binding factor expression (ICE)–C-repeat binding factor (CBF)–cold-regulated (COR) cascade is a central cold-response pathway. However, the molecular connection between BR signaling and this canonical defense system in tea plants has not been fully resolved, particularly in perennial crop tissues. Based on these challenges, there is a need to investigate how hormone signaling integrates with established cold-response pathways in tea plants.
Researchers from Guizhou University and the Guizhou Academy of Agricultural Sciences published (DOI: 10.1093/hr/uhag098) the study in Horticulture Research on 13 March 2026. The team investigated how the BR-responsive transcription factor CsBES1-14 regulates cold adaptation and identified the cold-regulated protein CsCOR413 as its direct downstream target. Through carefully integrated genetic, physiological, and biochemical analyses, the researchers showed that the CsBES1-14 – CsCOR413 regulatory module links BR signaling with the ICE–CBF–COR pathway, helping tea plants preserve membrane integrity, maintain antioxidant defenses, and withstand low-temperature stress.
The researchers first identified CsBES1-14 from transcriptome data obtained from cold-treated tea plants. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) showed that cold and brassinolide (BL) increased CsBES1-14 expression, whereas the BR inhibitor brassinazole (BRZ) suppressed it. Cellular assays localized the CsBES1-14 protein to the nucleus and confirmed its transcriptional activation activity. In Arabidopsis thaliana , overexpressing CsBES1-14 increased freezing survival, reduced electrolyte leakage and reactive oxygen species (ROS) accumulation, and elevated cold-responsive gene expression. Introducing CsBES1-14 into the bes1-1 loss-of-function mutant restored survival to 44%, close to the wild-type (WT) level. Virus-induced gene silencing (VIGS) in tea plants produced the reverse phenotype: silenced leaves showed greater yellowing and membrane damage, together with lower catalase (CAT) and superoxide dismutase (SOD) activities under cold stress. A transcription factor-centered yeast one-hybrid (Y1H) screen identified CsCOR413 as a candidate target. Y1H, dual-luciferase reporter, and electrophoretic mobility shift assay (EMSA) experiments then confirmed that CsBES1-14 binds two sites in the CsCOR413 promoter and activates transcription. Silencing CsCOR413 increased cold injury and electrolyte leakage, whereas overexpression improved tolerance. Additional experiments showed that CsCOR413 is also controlled by the ICE–CBF pathway, revealing convergence between two cold-defense systems.
The authors said the results show how a hormone signal associated with plant growth can be redirected into a protective response when temperatures fall. They said CsBES1-14 acts as a molecular connector rather than an isolated switch, activating CsCOR413 while operating alongside the ICE–CBF–COR pathway to reinforce membrane protection and antioxidant balance. This integrated mechanism helps explain why cold tolerance depends on coordination among multiple signaling routes. The study therefore provides a clearer view of how tea plants combine hormone perception, transcriptional regulation, and cellular protection to survive sudden low-temperature stress.
The CsBES1-14 – CsCOR413 module offers potential targets for marker-assisted selection, gene editing, and functional screening of cold-tolerant tea germplasm. Natural variation in these genes or their regulatory regions may help breeders identify cultivars that maintain leaf health and productivity during cold events. Because BR signaling and COR proteins are conserved across plant species, the mechanism may also inform studies of other perennial crops. However, most experiments were performed under controlled conditions, and part of the functional validation used A. thaliana . Field trials across tea cultivars, growth stages, and climates will be needed to determine whether manipulating this module can improve cold resilience without compromising growth, yield, tea quality, or other commercially important traits.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhag098
Funding information
This work was supported by t National Natural Science Foundation, grant numbers 32160077 and 32502773; Guizhou Province Major Project–Qiankehe Major Special Project, grant number 2024-027; Guizhou Provincial Basic Research Program (Natural Science), grant number Qiankehe Foundation ZD[2026]019; Guizhou Academy of Agricultural Sciences Outstanding Talent Team Special Project, grant number Qian-nong-keyuan Outstanding Team No. 2026-02.
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.
Horticulture Research
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The CsBES1-14-CsCOR413 module mediated by brassinolide positively regulates cold resistance in tea plant
13-Mar-2026
The authors declare that they have no competing interests.