Metabolic engineering of anthocyanins and condensed tannins in plants

Monomeric anthocyanins and polymeric proanthocyanidins (condensed tannins) contribute to important plant traits such as flower and fruit pigmentation, fruit astringency, disease resistance and forage quality. Recent advances in our understanding of the transcriptional control mechanisms that regulate anthocyanin and condensed tannin formation in plants suggest new approaches for the engineering of quality traits associated with these molecules. In particular, MYB family transcription factors are emerging as central players in the coordinated activation of sets of genes specific for the anthocyanin and tannin pathways. Mutations in these genes underlie potentially valuable crop traits, and ectopic over- or under-expression of MYB transcription factors provides routes for engineering of these complex pathways.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (170 K)Download as PowerPoint slideHighlight► Anthocyanins and condensed tannins confer important quality traits in plants. ► The many steps of anthocyanin biosynthesis are now well understood, but the mechanism of tannin polymerization is still unclear. ► Mutations in transcription factors underlie several useful pigmentation phenotypes in crop plants. ► Anthocyanins can be engineered to high levels through ectopic expression of MYB transcription factors. ► Tannin engineering can lead to bloat-safe forage crops.