Submitted to: Phytopathology
Publication Type: Proceedings
Publication Acceptance Date: August 13, 2003
Publication Date: September 9, 2003
Citation: Wheeler, M.H., Bruton, B.D., Stipanovic, R.D., Puckhaber, L.S. 2003. Identification and analysis of pentaketide and hexaketide metabolites in cultures of wild-type and degenerative isolates of Monosporascus cannonballus [abstract]. American Phytopathological Society. Paper No. P-2003-0660-AMA. Technical Abstract: Monosporascus cannonballus causes root necrosis and severe stunting of muskmelon and watermelon. Wild types of the fungus undergo degenerative changes over time in virulence, production of perithecia, and hyphal melaninization. In this study, PDA cultures of 10 typical yellow to brown colored degenerative strains of the fungus were found to accumulate appreciable amounts of the hexaketide 5-hydroxy-7-methoxy-4,9-dioxonaphthol[1,3-c]furan and four related compounds. These hexaketides were absent or present only in minute amounts in cultures of the 23 wild types studied. Also, it was shown with the melanin inhibitor tricyclazole that the wild types made melanin from 1,8-dihydroxynaphthalene. Melanin synthesis in the yellow to brown strains was disrupted as indicated by the accumulation of flaviolin, 2-hydroxyjuglone, and other pentaketide melanin metabolites. The relative importance of dsRNA elements in causing polyketide accumulation and other degenerative changes will be discussed.