A polyketide synthase that is involved in the production of the phytoalexin aucuparin. 2-Hydroxybenzoyl-CoA can also act as substrate but it leads to the derailment product 4-hydroxycoumarin (cf. EC 2.3.1.208, 4-hydroxycoumarin synthase) [2]. This enzyme uses the same starter substrate as EC 2.3.1.151, benzophenone synthase.