Abstract: Based on the transcriptome database of tea plants, the cDNAs ( CsFAD2 and CsFAD6) including full ORFs of the key rate-limiting enzyme-FAD (△12-fatty acid desaturase) in the unsaturated fatty acid synthesis pathway were cloned from the buds and leaves of tea cultivar Tieguanyin by RT-PCR .The full length of cDNA of CsFAD2 was 1 184 bp, which contained a 1β149βbp ORF encoding 382 amino acids with 97% homologous to the CoFAD2. Subcellular localization prediction showed that CsFAD2 was localized to the endoplasmic reticulum. The full length of cDNA of CsFAD6 was 1β425βbp and contained a 1β311βbp ORF encoding 436 amino acids, which was 81% homologous to VvFAD6. It was predicted to be located on the chloroplast. Quantitative PCR analysis showed that the expression of CsFAD2 and CsFAD6 were induced by cold stress (4℃), which had the highest expression levels at 48βh. Similarly, CsFAD2 and CsFAD6 were induced by 100βg·L^-1 PEG treatment for 12βh. The expression of CsFAD2 was significantly up-regulated under the treatment of ABA(100βμmol·L^-1 ) for 6-24βh. While the expression of CsFAD6 was not affected by ABA during this period and dramatically down-regulated at 72βh. The expression of CsFAD2 was repressed under NaCl (250βmmol·L^-1) treatment. Inversely;|the expression of CsFAD6 was significantly induced by NaCl treatment from 24 to 72βh.

Key words: Camellia sinensis, △12-fatty acid desaturase enzyme, abiotic stresses, gene expression