Using methods described in preferred embodiments, the composition of proanthocyanidins (PAs) in plants can be modified to produce plants that produce PAs with specific selections of catechin or epicatechin starter units, as well as specific selections of catechin or epicatechin extension units. Reduction or elimination of expression of the leucoanthocyanidin dioxygenase (ldox) gene or the anthocyanidin synthase (ans) gene, or both, is implemented in preferred embodiments to produce modified plants having modified PA content.