Figure 11.

A revised model for the function of VvLARs. The figure demonstrates that both VvLAR1 and VvLAR2 channel three PA extension units (denoted as “E”) to starter units (denoted as “S”) directly and indirectly. Dashed lines with question marks indicate proposed pathways. On the one hand, VvLARs directly convert leucocyanidin and Cys-C to (+)-catechin and Cys-EC to (−)-epicatechin. On the other hand, by consuming leucocyanidin, VvLARs may not only prevent Cys-C synthesis, but also compete with the synthesis of cyanidin to regulate the flow to Cys-EC.