Short-chain dehydrogenase; part of the gene cluster that mediates the biosynthesis of virensols and trichoxide, fungal natural products that contain or are derived from a salicylaldehyde core (PubMed:31790246). The pathway begins with the synthesis of the reduced chain in virensol C by the highly reducing polyketide synthase virA via condensation of one acetate and 8 malonate units (PubMed:31790246). VirA has interesting programming rules since the first 2 ketides are fully reduced, the 3 following ketides undergo beta-dehydration, and the last 3 ketides are only reduced to beta-hydroxys to yield the trihydroxy portion (PubMed:31790246). The production of aldehyde virensol C by virA alone is surprising, since virA does not contain a reductase (R) domain that is typically associated with reductive product release in HRPKS (PubMed:31790246). The cupin-domain enzyme virC is involved in enhancing virA product turnover (PubMed:31790246). The short-chain dehydrogenase virB then oxidizes the C-7 alcohol of virensol C to a ketone, yielding virensol D (PubMed:31790246). Virensol D is further transformed to salicylaldehyde 5-deoxyaurocitrin by the short-chain dehydrogenase virD (PubMed:31790246). VirD catalyzes the dehydrogenation of C-3 to form the beta-ketone aldehyde, which is followed by the generation of the nucleophilic C-2 that is required for the intramolecular aldol condensation between C-2 and C-7, itself followed by dehydration and aromatization which leads to salicylaldehyde 5-deoxyaurocitrin (PubMed:31790246). While the dehydrogenation of virensol D is definitely catalyzed by virD, the aldol condensation and dehydration may be uncatalyzed or assisted by virD (PubMed:31790246). The short chain dehydrogenase virG then converts salicylaldehyde 5-deoxyaurocitrin into virensol B which is further hydroxylated by the cytochrome P450 monooxygenase virE to yield the hydroquinone virensol A (PubMed:31790246). VirI then may oxidize virensol A to form the quinone, while virH performs the epoxidation (PubMed:31790246). Finally, the two remaining short-chain dehydrogenases, virK and virL, are probably responsible for reducing the ketones to the corresponding alcohols to furnish the epoxycyclohexanol structure in trichoxide (PubMed:31790246). Secondary metabolite biosynthesis. Belongs to the short-chain dehydrogenases/reductases (SDR) family.