Scytalone dehydratase-like protein; part of the gene cluster that mediates the biosynthesis of the bianthraquinone cladofulvin, a conidial pigment not required for virulence but that plays a role in fitness and resistance to environmental stresses including UV light and low-temperature stress (PubMed:24465762, PubMed:27274078). The pathway begins with the synthesis of atrochrysone thioester by the polyketide synthase (PKS) claG. The atrochrysone carboxyl ACP thioesterase claF then breaks the thioester bond and releases the atrochrysone carboxylic acid from claG (PubMed:27274078). This compound is decarboxylated by claH to yield emodin, which is further converted to chrysophanol hydroquinone by the reductase claC and the dehydratase claB (PubMed:27274078). The cytochrome P450 monooxygenase claM then catalyzes the dimerization of nataloe-emodin to cladofulvin (PubMed:27274078). Pigment biosynthesis. Expression is positively regulated by the transcriptional regulator wor1 (PubMed:24521437, PubMed:27274078). Expression is down-regulated during biotrophic growth within tomato leaves (PubMed:27997759). Belongs to the scytalone dehydratase family.