SWEET tea: transcriptional regulation of sugar transporters in stress and development

Cold stress is a major factor limiting the growth, distribution, and yield of tea (Camellia sinensis). Under low temperatures, tea plants accumulate soluble sugars as osmoprotectants, a process facilitated by transporters such as CsSWEET17. However, upstream regulatory mechanisms controlling CsSWEET17 have been unclear until now. Using a yeast one-hybrid screen, Peng et al. (2025) identified CsDREB28, a cold-inducible DREB transcription factor with an EAR repression motif, as a direct repressor of CsSWEET17 and CsSWEET15. CsDREB28 expression rapidly increased under cold stress. Silencing CsDREB28 in tea plants enhanced CsSWEET17 expression in leaves, increased sugar content, and improved freezing tolerance. In contrast, overexpression in Arabidopsis caused cold sensitivity, early senescence, growth inhibition, and reduced seed yield. The study uncovers a regulatory module in which CsDREB28 negatively controls SWEET sugar transporters, which, besides sugar allocation and cold tolerance, also seem to function in plant development. Thereby, it deepens our understanding of sugar transport regulation in response to abiotic stress in plants.