Anthrone oxygenase; 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). emodin anthrone + O2 = emodin + H(+) + H2O Secondary metabolite biosynthesis. Expression is positively regulated by the cluster-specific transcription factor MYCFIDRAFT_198930 and is up-regulated during banana leaves infection. Belongs to the anthrone oxygenase family.