Abstract: In this experiment，the cDNA sequences of five fatty acid desaturase（FAD）family genes were cloned from the tea plant cultivar‘Tieguanyin’by RT-PCR，and named as CsFAD2-2，CsFAD3，Δ7-CsFAD，Δ8-CsFAD and CsFAB2，respectively. The length of coding sequences were ranged from 1 137 to 1 320 bp. Phylogenetic and motif analysis showed that CsFAD members could be divided into four subfamilies，including the ω3/ω6-FAD subfamily，the Δ7/Δ9-FAD subfamily，the Front end FAD subfamily，and the FAB subfamily. The conserved motifs of FAD members were identical in the same subfamily，while they were quite different in different subfamilies. The results of quantitative real-time PCR indicated that all of CsFAD genes were significantly induced in response to low temperature treatment，especially the expression level of Δ8-CsFAD could be strongly up-regulated to thousand folds. After exogenous ABA treatment，the expression level of CsFAD genes was up-regulated to more than two folds except for CsFAD3. Under drought stress，the expression levels of CsFAD2-2，Δ7-CsFAD and Δ8-CsFAD were up-regulated to more than 1.5 folds，and the expression of Δ8-CsFAD was induced to 5.5 folds，whereas the expression of CsFAD3 and CsFAB2 was significantly repressed by drought treatment. Moreover，we isolated the Δ8-CsFAD promoter sequence and analysis results showed that it contains multiple stress responsive cis-elements. Subcellular localization analysis in tobacco indicated that Δ8-CsFAD was localized to the cell membrane. Our results showed that CsFAD genes might be involved in the tea plants stress response，especially of Δ8-CsFAD，reflecting that they could regulate the synthesis of unsaturated fatty acids in the cell membrane to participate in the stress resistance of tea plants.

Key words: Camellia sinensis, fatty acid desaturase, adversity stress, promoter, subcellular localization