Reducing polyketide synthase that catalyzes the formation of a C22 intermediate attached to the ACP. Release by intramolecular hydrolysis by the enolized delta-carbonyl would give the pyrone product aslanipyrone (PubMed:16642517). Alternatively, KR-mediated reduction of the beta-carbonyl of the C22 intermediate would form a beta-hydroxy thioester intermediate, which could be a substrate for a further KS-mediated condensation of an additional C2 unit to form a C24 intermediate, which cyclizes by aldol condensation followed by decarboxylation to form aslaniol (PubMed:16642517). Neither aslanipyrone, aslaniol, nor their derivatives have been detected in A.solani, probably due to a low abundance and/or extensive post-PKS modification. It is assumed that the branching point from C22 to C24 is the result of KR activity on the C22 intermediate anchored to the ACP (PubMed:16642517). Binds 1 phosphopantetheine covalently. Multidomain protein; including a ketosynthase (KS) that catalyzes repeated decarboxylative condensation to elongate the polyketide backbone; a malonyl-CoA:ACP transacylase (MAT) that selects and transfers the extender unit malonyl-CoA; a dehydratase (DH) domain that reduces hydroxyl groups to enoyl groups; an enoylreductase (ER) domain that reduces enoyl groups to alkyl group; a ketoreductase (KR) domain that catalyzes beta-ketoreduction steps; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm (Probable). The ER domain was found to be much shorter than those of other fungal RD-PKSs, and in its nucleotide-binding domain (G/AxGxxG), the second glycine is replaced by a serine residue. This suggests that this domain is non-functional and is consistent with the absence of reduction of the double bonds formed by the DH domain in the PKSF products (Probable).