New perspectives on the biosynthesis, transportation, astringency perception and detection methods of grape proanthocyanidins

Proanthocyanidins (PAs) are important secondary metabolites crucial for the quality of grape berry and wine. Despite important advances in our understanding of the structural and regulatory genes involved in the PAs biosynthesis pathway, our knowledge about the details of biosynthetic and regulatory networks, especially the mechanism of polymerization and transportation remains limited. We provided an overview of the latest discoveries related to the mechanisms of grape PAs structure, astringency properties, detection methods, biosynthesis and transportation. We also summarized the environmental influencing factors of PAs synthesis in grape. Future trends were discussed.