Genome-Wide Analysis of Tea FK506-Binding Proteins (FKBPs) Reveals That CsFKBP53 Enhances Cold-Stress Tolerance in Transgenic Arabidopsis thaliana

FK506-binding proteins (FKBPs) belong to the peptidyl-prolyl cis/trans isomerase (PPIase) superfamily and are involved in a wide range of biological processes including protein folding, hormone signaling, plant growth, and stress responses. However, the FKBPs and their biological functions have not been identified in tea plants. In this study, 21 FKBP genes were identified using the conserved FK506-binding domain (PF00254) in the tea-plant genome. Their phylogeny, classification, structure, motifs, interactors, and expression patterns were analyzed. Comprehensive qRT-PCR analysis revealed distinct expression patterns of CsFKBPs in different tissues and in response to low temperature. Through a comprehensive genome-wide analysis, we characterized the low-temperature expression dynamics of the CsFKBP53 gene family and demonstrated that its overexpression significantly enhances cold tolerance in Arabidopsis. Notably, the transcript levels of CsFKBP53 exhibited pronounced variability across distinct tea (Camellia sinensis) cultivars under cold-stress conditions. These findings not only underscore the functional conservation of FKBP-type immunophilins across plant lineages but also highlight the biotechnological potential of CsFKBP53 as a genetic modulator of low-temperature resilience in crops. By integrating comparative genomics and functional validation, our study establishes a foundation for leveraging conserved stress-response mechanisms to engineer climate-resilient plants.