Type III polyketide synthase involved in the biosynthesis of the phytoalexins bisphenyls and dibenzofurans. Can also use salicoyl-CoA and malonyl-CoA to produce a diketide intermediate yielding 4-hydroxycoumarine after cyclization and enolization. Can also use m-hydroxybenzoyl-CoA as substrate, producing m-hydroxybenzoyl diacetic acid lactone as a derailment product. No activity with p-hydroxybenzoyl-CoA, CoA-linked cinnamic acids or acetyl-CoA. benzoyl-CoA + 3 H(+) + 3 malonyl-CoA = biphenyl-3,5-diol + 4 CO2 + 4 CoA kcat is 0.43 min(-1) with benzoyl-CoA as substrate. kcat is 0.27 min(-1) with salicoyl-CoA as substrate. Optimum pH is 6.5-7.0. Optimum temperature is 35 degrees Celsius. Homodimer. Up-regulated by elicitor and by endogenous H(2)O(2). Belongs to the thiolase-like superfamily. Chalcone/stilbene synthases family.