Journal of Tea Science Research, 2024, Vol.14, No.6, 322-334 http://hortherbpublisher.com/index.php/jtsr 329 typical oolong tea aroma substances, such as indole, (E)-β-farnesene, (E)-geraniol, jasmine lactone and linalool; the related synthase genes (e.g., TSB2, OCS, NES, AFS, LOX1) and the key genes of the upstream MVA, MEP, and ALA metabolic pathways were expressed at higher levels in CG than in F6 (Figure 3). This difference was confirmed to be closely related to the higher level of JA, especially methyljasmonic acid (MeJA) accumulation in CG after mechanical stress. Figure 3 Transcript profiling of key differential genes in the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways in Chungui (CG, Camellia sinensis) and Fuyun No. 6 (F6, Camellia sinensis) varieties before and after mechanical stress. Heat map representation of the expression level of key genes is shown in the figure. Gene expression is displayed as a heat map depicting the log2 (FPKM) values. Red and blue dots and size indicate up- and downregulated genes, respectively (Adopted from Li et al., 2024a) Image caption: In the figure, red indicates upregulation and blue indicates downregulation, clearly showing that CG exhibits higher expression levels of aroma precursor synthesis-related genes such as CsDXS, CsGGPS, and CsispE. The results suggest that CG enhances the synthesis of precursor substances after mechanical stress, thereby promoting the accumulation of aroma compounds in oolong tea. This provides molecular evidence supporting the formation of aroma differences between tea varieties (Adapted from Li et al., 2024a) Further weighted gene co-expression network analysis showed that 34 transcription factors (such as MYC2, WRKY, bZIP, etc.) were involved in regulating the expression of JA response pathways and aroma synthesis genes. The active expression of m6A RNA demethylase CsALKBH10B in CG may stabilize key enzyme mRNAs and enhance aroma synthesis (Li et al., 2024a). The study revealed the dominant role of JA and its signal transduction in the formation of oolong tea aroma, providing a molecular basis for the breeding and regulation of future excellent aroma tea varieties.
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