Indentification of key regulatory genes associated with high dihydromyricetin contents in different vine tea germplasms

Abstract Zhangjiajie vine tea, derived from Ampelopsis grossedentata , is a characteristic product with pharmacological benefits for heat clearance, detoxification, liver calming, and blood pressure reduction. The content of dihydromyricetin (DMY), the primary active compound, directly affects product quality, yet the regulatory genes associated with high DMY contents remained to be determined. In this study, a total of 164 vine tea germplasms collected from Zhangjiajie were revealed to exhibit substantial variation in DMY contents, ranging from 13.96 to 41.56% with a mean of 29.55%. Among them, 73 possessed DMY contents ≥ 30%. Comparative transcriptome analysis between J25-1 (DMY ≥ 30%) and J16 (an accession of low DMY content) revealed that a total of 2,044 differentially expressed genes (DEGs) in June, 939 up-regulated and 1105 down-regulated, were identified in J25-1 relative to J16. In August, 3,051 DEGs were identified, including 1,403 upregulated and 1,648 downregulated genes in J25-1 relative to J16. The DEGs were significantly enriched in the endoplasmic reticulum protein processing pathway and stress-response pathways, such as heat shock proteins indirectly associated with DMY metabolism by maintaining protein homeostasis. Of note, J25-1 displayed downregulation of flavonol synthase ( FLS ), MCM1-AGAMOUS-DEFICIENS-SRF ( MADS ) -box and peroxidase ( POD ) genes, which may be implicated in the repressed conversion of DMY to myricetin, promotion of secondary metabolite allocation or flow toward the DMY synthesis. This study systematically elucidates the transcriptional reprogramming for influencing DMY biosynthesis in vine tea germplasms. The elite accession with high DMY contents, J25-1, can serve as a high-quality breeding resource, and the identified genes provide targets for molecular breeding in the future.