Short chain dehydrogenase; part of the gene cluster that mediates the biosynthesis of an emodin derivative that may be involved in black Sigatoka disease of banana (PubMed:27388157, PubMed:30735556). The pathway begins with the synthesis of atrochrysone thioester by the polyketide synthase PKS8-1 (Probable). The atrochrysone carboxyl ACP thioesterase MYCFIDRAFT_190111 then breaks the thioester bond and releases the atrochrysone carboxylic acid from PKS8-1 (Probable). The decarboxylase MYCFIDRAFT_34057 then catalyzes the concerted decarboxylation-elimination required to convert atochrysone carboxylic acid into emodin anthrone, which is further oxidized to emodin by the anthrone oxygenase MYCFIDRAFT_34418 (Probable). The functions of the other tailoring enzymes as well as the final product of the cluster have still to be identified (Probable). Secondary metabolite biosynthesis. Belongs to the short-chain dehydrogenases/reductases (SDR) family. Extended N-terminus. Extended C-terminus.