Abstract: In this study, five sequences of the amino acid permease (AAP) genes were successfully cloned from tea cultivar Longjing 43 by RT-PCR. The amino acid sequence alignment analysis revealed the high homology among the five CsAAP proteins (70.27%). Phylogenetic tree based on amino acid sequences showed that five CsAAPs could be classified into three groups. Further bioinformatics analysis demonstrated that these CsAAPs contained 9-10 transmembrane structures and 16-18 conserved AAP motifs. To investigate the response of this subfamily to nitrogen, cutting seedlings of three tea cultivars were fed with NH₄NO₃ of different concentrations after two weeks of nitrogen starvation and then used for qRT-PCR analysis. The results show that these five CsAAPs were expressed in all vegetative tissues of tea cutting seedlings, but there were certain differences in tissue expressions. Among them, CsAAP3 showed the highest gene expression levels in stems and the main expression sites of CsAAP8 were roots and stems. The expression levels of CsAAPs varied temporally and spatially with nitrogen treatments. The gene expression of CsAAP3 was significantly changed among the tea cultivars with different nitrogen use efficiency. The expressions of CsAAP3 and CsAAP8 in the stem of the high nitrogen efficient cultivar Zhongcha 302 could quickly respond to low nitrogen levels. Their gene expression levels were increased significantly after 3 h of the low nitrogen treatment. These results implies that CsAAPs subfamily might play important roles in the regulation of nitrogen metabolism through the intricate transports of amino acids in tea plants.

Key words: Camellia sinensis, amino acid permeases (AAPs), gene cloning and expression, nitrogen