Non-reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of dihydroxynaphthalene (DHN)-melanin, a bluish-green pigment and a structural component of the conidial wall (PubMed:9620950, PubMed:10515939, PubMed:18539819, PubMed:19156203). The first step of the pathway is the production of the heptaketide naphtopyrone YWA1 by the polyketide synthase alb1 though condensation of acetyl-CoA with malonyl-CoA (PubMed:9620950, PubMed:11040426). The naphtopyrone YWA1 is then converted to the pentaketide 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) by the heptaketide hydrolyase ayg1 though chain-length shortening (PubMed:10515939, PubMed:11350964). 1,3,6,8-THN is substrate of the hydroxynaphthalene reductase arp2 to yield scytalone (PubMed:10515939). The scytalone dehydratase arp1 then reduces scytalone to 1,3,8-THN (PubMed:10515939). 1,3,8-THN is also substrate of the hydroxynaphthalene reductase arp2 to yield vermelone (PubMed:10515939). Vermelone is further converted by the multicopper oxidase abr1 to 1,8-DHN (PubMed:10515939). Finally the laccase abr2 transforms 1,8-DHN to DHN-melanin (PubMed:10515939). DHN-melanin biosynthesis appears to be initiated in endosomes where early enzymes (abl1, ayg1, arp1 and arp2) localize, with exocytosis leading to melanin deposition on the cell surface where late enzymes (abr1 and abr2) localize (PubMed:26972005). DHN-melanin is an important structural component of the outer cell wall and is required for the presence of conidial surface hydrophobins (PubMed:19703288). DHN-melanin also plays a crucial role in fungal virulence, including a protective role against the host's immune defenses (PubMed:9620950, PubMed:9832321, PubMed:12464010,PubMed:16110796, PubMed:20145078, PubMed:21501368, PubMed:21747802, PubMed:21573171, PubMed:24818666, PubMed:24836942, PubMed:25810442, PubMed:26972005). DHN-melanin protects also conidia against amoeba predation (PubMed:25684622). acetyl-CoA + 6 H(+) + 6 malonyl-CoA = 6 CO2 + 7 CoA + H2O + YWA1 Pigment biosynthesis; melanin biosynthesis. Expression is up-regulated by laeA during mycelial growth in a liquid medium but laeA is not involved in alb1 regulation during conidial morphogenesis (PubMed:17630330). Expression is, at least in part, controlled by the cAMP/PKA signal transduction pathway (PubMed:16110796). Multidomain protein; including a starter unit:ACP transacylase (SAT) that selects the starter unit; 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 product template (PT) domain that controls the immediate cyclization regioselectivity of the reactive polyketide backbone; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm (By similarity). The C-terminal region is involved in Claisen-type cyclization of the second ring of naphthopyrone. Impairs the production of melanin and leads to an albino phenotype (PubMed:9620950, PubMed:15321679, PubMed:15812003, PubMed:17343676, PubMed:19156203, PubMed:26701308). Blocks the synthesis of the intermediate 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) (PubMed:9620950). Results in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface (PubMed:19703288, PubMed:24818666, PubMed:26972005). Results also in a dramatic reduction of virulence in a mice models of infections (pulmonary and cutanous) with efficient complement component C3 binding on conidial surfaces and increased neutrophil-mediated phagocytosis (PubMed:9620950, PubMed:9832321, PubMed:12464010, PubMed:20145078, PubMed:21501368, PubMed:21747802, PubMed:21573171, PubMed:24836942). Decreases also the protection of conidia against amoeba predation (PubMed:25684622). Decreases significantly the ability of conidia to activate platelets and to induce platelet aggregation (PubMed:25810442). Causes enhanced insect mortality compared to the parent strain in a wax moth Galleria mellonella infection model, probably through exacerbated immune response of the wax moth (PubMed:19156203).