关键词: 茶树, LHTs, 氮素, 基因克隆与表达

Abstract: Amino acids are important quality components and forms of nitrogen storage in tea plants (Camellia sinensis). Therefore, it is of great significance to study the function of amino acid transporters. In present study, five LHTs (Lysine histidine transporters, CsLHTs) were found from transcriptomes of tea plants. Among them, four CsLHTs were successfully cloned from the cultivar ‘Longjing 43’ by RT-PCR, and named CsLHT1, CsLHT6, CsLHT8.1 and CsLHT8.2, respectively. The prediction results from amino acid sequences showed that each of CsLHT contained 9-11 transmembrane domains and one domain of amino acid transporter. To investigate the expression patterns of these CsLHT genes under different nitrogen levels, cutting seedlings of three tea cultivars were fed with NH₄NO₃ of three levels (0.2 mmolL^-1, 2 mmolL^-1 and 10 mmolL^-1) after two weeks of nitrogen starvation. The qRT-PCR results showed that four CsLHTs were expressed in all vegetative tissues, and exhibited diverse expression patterns. For the genes of CsLHT1, CsLHT6 and CsLHT8.2, the gene expression were affected more highly by tea cultivars rather than by nitrogen levels. However, the gene expression of CsLHT8.1 changed greatly by nitrogen treatments. Especially, after 72 h treatments of 0.2 mmolL^-1 and 10 mmolL^-1 NH₄NO₃, the CsLHT8.1 expressions were significantly up-regulated in the root of ‘Zhongcha 302’, which was identified as a high nitrogen efficient cultivar. These results implied that CsLHT8.1 might participate in the transport of amino acids from root to aerial parts in tea plants.

Key words: Camellia sinensis, Lysine histidine transporters (LHTs), nitrogen, gene cloning and expression