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Triglycerides and Cercosporin from Cercospora beticola: Fungal Growth and Cercosporin Production. Constantine Balis, Postdoctoral Fellow, Department of Chemistry, Colorado State University, Fort Collins 80521, Present address of senior author: Department of Industrial Microbiology, University College, Ardmore, Stillorgan Road, Dublin 4, Ireland; Merle G. Payne, Professor, Department of Chemistry, Colorado State University, Fort Collins 80521. Phytopathology 61:1477-1484. Accepted for publication 15 July 1971. DOI: 10.1094/Phyto-61-1477.

Compounds which are phytotoxic to sugar beet leaves were isolated from Cercospora beticola. The factors affecting their production and chemical composition were studied. They were identified as cercosporin, and mixtures of triglycerides having octadecenoic, octadecadienoic, octadecatrienoic, and hexadecanoic acids. Auto-oxidation products of fatty acids were also detected. Analytical and spectrometric data suggest that the molecular formula of cercosporin is C2 9H2 6O10. Cercosporin was found to be photosensitive at pH values higher than 7.7. Inhibition of growth of C. beticola and enhancement of cercosporin production were induced by light only in colonies growing on media supplied with ascorbic acid.

Additional keywords: characterization, photodecomposition, nuclear magnetic spectrum.