Genomic Study Maps the Biosynthesis of Dihydromyricetin in Vine Tea

Vine tea has been consumed in China for centuries and is valued as both a beverage and a medicinal plant. It is especially notable for its rich flavonoid content, with dihydromyricetin standing out as a major compound linked to antioxidant and other bioactive properties. Yet despite growing interest in vine tea for functional foods, cosmetics, and health-related products, researchers have lacked a reference-grade genome and a clear explanation for why different cultivars vary so widely in metabolite content. Based on these challenges, deeper research is needed on the genetic mechanisms controlling dihydromyricetin biosynthesis and diversity in vine tea.

Researchers from South China Normal University, the Agricultural Genomics Institute at Shenzhen of the Chinese Academy of Agricultural Sciences, South China Agricultural University, and the Guangdong Academy of Agricultural Sciences reported (DOI: 10.1093/hr/uhaf307) on November 18, 2025, in Horticulture Research that they had generated the first chromosome-scale pan-genome for vine tea and identified structural variation linked to differences in dihydromyricetin accumulation across cultivated accessions.

The team first produced haplotype-resolved genome assemblies for two major cultivated vine tea types, one green-leaf and one purple-leaf, generating chromosome-scale references with strong completeness and continuity. They then resequenced 39 cultivars collected from major production regions in southern China and used those data to construct a pan-genome, which revealed extensive diversity in gene families, structural variants, and geographically patterned population structure. Phylogenetic analysis further showed that vine tea diverged from Cissus rotundifolia about 26.67 million years ago and from grapevine about 17.30 million years ago.

The most striking finding came from linking genomic variation to metabolite data. Dihydromyricetin levels varied dramatically across the 39 cultivars, from almost undetectable levels in some lines to 27.1 g/100 g in cultivar W22. By combining transcriptome profiling, co-expression analysis, and structural variant screening, the researchers identified a 1038-bp deletion in the promoter–first exon region of NgF3′5′H in low-dihydromyricetin cultivars. Expression of NgF3′5′H was sharply reduced in those lines, and functional assays showed that the gene promotes conversion toward dihydromyricetin. The deleted version also lost proper membrane localization and showed weaker promoter activity, offering a direct molecular explanation for metabolic differences among varieties.

The study shows that vine tea's chemical diversity is not random; it is written into the architecture of its genome. By pinpointing structural variation around NgF3′5′H, the researchers provide a concrete target for understanding and potentially improving the biosynthesis of a high-value flavonoid. More broadly, the work demonstrates how pan-genomics can turn a traditional herbal crop into a genetically tractable system for studying specialized metabolism, domestication, and cultivar improvement.

This research creates a practical foundation for breeding vine tea with more consistent quality and stronger bioactive profiles. Markers linked to NgF3′5′H variation could help breeders screen germplasm for higher dihydromyricetin content, while the broader pan-genome offers a reference for discovering additional genes tied to flavor, adaptation, and medicinal value. Beyond vine tea itself, the study provides a model for upgrading underexplored herbal crops through genome-guided selection. In the long term, that could support more precise development of functional beverages, natural antioxidants, and plant-based health products with clearer molecular traceability.