Abstract: In recent years, extreme low-temperature weather has frequently occurred worldwide, significantly affecting the yield and quality of tea plants. The ICE (Inducer of CBF expression) gene family plays a crucial role in the low-temperature stress response of plants. However, research specifically focused on tea plants is still limited. This study identified 51 ICE genes from the tea genome and performed a bioinformatics analysis to examine their physical and chemical properties, gene structure, and promoter cis-acting elements. The promoter regions of the CsICE genes are rich in cis-acting elements related to light response, plant hormones, growth and development, and abiotic stress, suggesting their involvement in various stress responses. Transcriptome analysis and RT-qPCR verification indicate that the expression of the CsICE43 increased 4.24 folds under low-temperature conditions, highlighting its potential role in the low-temperature response of tea plants. To further investigate this, the cDNA of tea cultivar‘Baojing Golden Tea No. 1’ was used as a template to clone the CsICE43 gene. Its expression varied across tissues, with exceptionally high levels observed in terminal buds and young leaves. Further amino acid sequence and phylogenetic tree analysis indicate that the CsICE43 gene contains conserved domains such as S-rich, bHLH, and ACT, which are consistent with other members of the ICE family. It is closely related to Actinidia eriantha. The STRING online database utilized Arabidopsis thaliana AtICEs to hypothesize potential interactions between CsICE proteins and HOS1, MYB15, and DREB1/2. Subcellular localization experiments demonstrate that CsICE43 is located in the nucleus, which is consistent with the findings from the transmembrane structure analysis. In summary, this study suggests that the CsICE43 gene may be associated with the low-temperature response in tea plants, providing a theoretical foundation for further exploration of its gene function and the molecular mechanisms underlying cold resistance.

Key words: Camellia sinensis, ICE gene family, cold resistance, bioinformatics, expression analysis