Abstract: Tea is one of the important cash crop in China. Its growth and development will be affected by different adversity, leading to the decline of tea quality and yield. Light-harvesting chlorophyll-protein complex mainly affects the photosynthetic efficiency of plants, and also plays important roles in adaptation to environmental stresses. In order to study the characteristics of the light-harvesting chlorophyll-protein complex in tea plants, the gene CsLhcb2 encoding the light-harvesting protein complex was cloned from tea cultivar ‘Longjing 43’, and the sequence characteristics, phylogenetic tree, physical and chemical properties, subcellular localization, secondary structure, tertiary structure and its expression profiles under low temperature treatment were analyzed. The results show that the open reading frame of CsLhcb2 gene is 798 bp, encoding 265 amino acids. This gene contains a typical of Chloroa-b-bind conservation domain. The similarity of CsLHCB2 amino acid sequence with 15 plant species was 91.32%. Phylogenetic tree analysis shows that the CsLHCB2 protein of tea plant was closely related to Datura stramonium, Sedum alfredii and Vitis vinifera, and far from Dendrocalamus latiflorus and Phyllostachys edulis. The relative molecular weight of CsLHCB2 protein is 28 662.77 and the theoretical isoelectric point is 5.69, which belongs to hydrophilic protein. Subcellular localization prediction results show that CsLHCB2 protein is mainly located in chloroplasts. Quantitative RT-PCR results show that CsLhcb2 gene may participate in the process of low temperature stress in tea plants. Under normal temperature treatment, the relative expression level of CsLhcb2 gene showed a trend of increasing first and then decreasing within a photoperiod (24 h). ‘Longjing 43’ and ‘Shuchazao’ reached their peak value at 1 h after light treatment, and 'Baiyeyihao' reached their peak value at 6 h after light treatment. Under low temperature of 4 ℃ treatment, the expression of Lhcb2 of the three tea cultivars all reached the peak at 12 h of light treatment, among which the expression level of CsLhcb2 in ‘Shuchazao’ was the highest, which was 1.18 and 1.98 times higher than that of ‘Longjing 43’ and ‘Baiyeyihao’, respectively. The results provided a reference for further research on the role of light-harvesting chlorophyll-protein complex response to low temperature in tea plants.

Key words: Camellia sinensis, light-harvesting chlorophyll-protein complex, low temperature stress, expression analysis