Dirigent proteins impart stereoselectivity on the phenoxy radical-coupling reaction, yielding optically active lignans from two molecules of coniferyl alcohol in the biosynthesis of lignans, flavonolignans, and alkaloids and thus plays a central role in plant secondary metabolism. Homodimer. Upon contact with the plant pathogens fungus Fusarium solani, Pseudomonas syringae pv pisi, and the fungal elicitor chitosan. Belongs to the plant dirigent protein family.