Highly reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of nectriapyrone and its analogs phomopyrone A, acropyrone and zaepyrone (PubMed:30443971). The nectriapyrone biosynthetic gene cluster consists of two genes, the highly reducing polyketide synthase NEC1 that produces a demethylated analog of nectriapyrone from one unit of acetyl-CoA and one unit of malonyl-CoA; and the O-methyltransferase NEC2 that further methylates the NEC1 product to yield nectriapyrone (PubMed:30443971). Nectriapyrone is further hydrolyzed to nectriapyrone D, also known as gulypyrone B, by an unidentified hydrolase localized outside the nectriapyrone cluster (PubMed:30443971). 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; a methyltransferase (CMeT) domain responsible for the incorporation of methyl 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. Completely abolishes the production of nectriapyrones.