Screening and Expression Analysis of Key Regulator Gene Associated with α-Farnesene Formation during Manufacturing Process of Oolong Tea

For purpose of understanding the influence of mechanical force during the turning-over process on the formation of α-farnesene, in this experiment, fresh tea leaves, solar withering tea leaves, turned-over tea leaves of the oolong tea cultivar Camellia sinensis cv.Huangdan as test materials and spread tea leaves (collected at the same time point) as control group were detected by headspace-gas chromatograpy-mass spectrometry (GC-TOF-MS).Thereafter, α-farnesene synthase (AFS) gene was selected based on Tea Tree Genemo Database and phylogenetic tree was constructed. The data were measured by quantitative real-time PCR and the relative correlation between α-farnesene content and relative gene expression level was also analyzed. The results indicated that although the α-farnesene content in first-time turned-over leaves decreased under the mechanical force, it still increased gradually with the treatments and reached the peak at the third-time turned-over point (0.9485%).The CL11384.Contig7_All gene was remarkably similar to CsAFS (GenBank accession no. MH125264.1), so CL11384.Contig7_All gene was named as CsAFS7 tentatively since the gene expression pattern was corresponding with the sequencing data. The correlation between α-farnesene content of manufacturing-process oolong tea and relative expression level of CsAFS7 gene were evaluated by Pearson correlation coefficient, and the results showed that there was a significant positive correlation (r=0.951, P<0.01). To sum up, the accumulation of α-farnesene content during manufacturing process might be regulated by CsAFS7 gene expression manipulation.