Abstract:In this study, a CsBAP1 gene was cloned from the cDNA of ‘Longjing 43’ based on the transcriptome data of tea plant. We analyzed its protein sequence characteristics and gene expression patterns. In addition, the expression profiles of the CsBAP1 gene in different tissues and under extreme temperatures and hormone treatments in tea plant was analyzed by quantitative real time PCR. (1) Sequence analysis showed that the length of the CsBAP1 open reading frame (ORF) is 543 bp, encoding 180 amino acids and contains a highly conserved region called C2 domain. Protein analysis suggested that the CsBAP1 is a hydrophilic protein with the theoretical relative molecular weight 19 398 Da and the theoretical isoelectric point 9.30. Secondary structure prediction showed that the CsBAP1 protein consists of 8.89% αhelix, 7.78% βturn, 35.56% extended strand and 47.78% random coil. The threedimensional structures indicated that CsBAP1 protein contains αhelix and βstrands. (2) The expression profiles of the CsBAP1 was detected in flower, floral buds, young leaves, mature leaves and senescent leaves by the RTqPCR. And the highest expression level was detected in the senescent leaves. The expression level of CsBAP1 was downregulated by ABA, IAA, MeJA, GA3, and SA treatments, respectively. The expression level of CsBAP1 was upregulated under high temperature (38 ℃), low temperature (4 ℃), drought (200 g·L-1 PEG), and highsalinity (200 mmol·L-1 NaCl) treatments, respectively. These results provide a foundation for the function study of CsBAP1 gene in tea plants.