Identification of candidate genes related to glycoside aroma precursor content in tea plant using WGCNA

By analyzing transcriptome data from tender shoots of different tea cultivars in autumn, key genes involved in the regulation of glycoside aroma precursor (GAP) biosynthesis were identified. This study provides a theoretical foundation for elucidating the biosynthetic mechanisms of GAPs and for guiding the breeding of tea cultivars with high GAP content. Tender shoots from 14 tea cultivars were used to quantify eight types of GAPs. Weighted gene co-expression network analysis (WGCNA) was applied to integrate transcriptomic data with GAP content, enabling the identification of co-expression modules and candidate genes related to GAP biosynthesis and accumulation. The distribution of the eight GAP types in tender shoots was uneven, with phenylpropanoid-type GAPs showing significantly higher accumulation than terpene-type GAPs. A total of 4277 differentially expressed genes (DEGs) were identified by comparing high-GAP and low-GAP cultivars. Quantitative real-time polymerase chain reaction (qRT-PCR) validation of selected DEGs showed results consistent with transcriptomic data, confirming the reliability of the analysis. WGCNA identified 26 co-expression modules, among which four modules—MEorange, MEyellow, MEdarkturquoise, and MElightcyan—were significantly correlated with the main GAP types (<italic>P</italic> &lt; 0.01). GO and KEGG enrichment analyses were performed on genes within these key modules. Based on gene connectivity and functional annotation, 16 key genes were identified, including 13 structural genes (four <italic>GSTs</italic>, three <italic>GTs</italic>, three <italic>TPSs</italic>, one <italic>CYP450</italic>, one <italic>CHI</italic>, and one <italic>DFR</italic>) and three transcription factor genes (two <italic>NACs</italic> and one <italic>WRKY</italic>). The seasonal variation in terpene- and phenylpropanoid-type GAP accumulation in autumn was notable, and the identified genes are likely to play central roles in regulating GAP biosynthesis and accumulation in tender tea shoots.