SUMMARYThe quinones, juglone, 2-hydroxyjuglone and 3-hydroxyjuglone, and the tetralones, (+)-3,4-dihydro-4,8-dihydroxy-1(2H) naphthalenone and (-)-cis-3,4-dihydro-3,4,8-trihydroxy-1 (2H) naphthalenone were isolated and identified from culture filtrates of the melanin-deficientbrm-2 mutant ofVerticillium dahliae.The probable origin of these metabolites from (+)-scytalone[3,4-dihydro-3,6,8-trihydroxy-1 (2H) napthalenone] via 1,3,8-trihydroxynaphthalene was shown. The genetic lesion in thebrm-2 mutant apparently prevents conversion of 1,3,8-trihydroxynaphthalene to (-)-vermelone [3,4-dihydro-3,8-dihydroxy-1(2H)-naphthalenone] in the biosynthetic pathway from (+)-scytalone to melanin.