Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 1, 2002
Publication Date: December 1, 2002
Citation: pp.151-155 In: Sorghum and Millet Diseases (J. F. Lester, ed.) Iowa State Press, Ames, 1A.504pp. Interpretive Summary: The fungal pathogen Claviceps africana causes ergot disease of sorghum. Major losses due to ergot have been sustained in many of the world's sorghum-growing regions. The disease came to the U.S. in 1997, spread rapidly, and caused alarm among sorghum growers. Genetic diversity in the ergot pathogen was analyzed using a collection of pathogen isolates made from worldwide sources. Strains of the fungus from different parts of the world were grouped based on their similarity for DNA based markers, and it was found that U.S. strains grouped with strains from Mexico and Africa, as distinct from strains from Japan, Australia, and India. Diversity was found among isolates from the new U.S. population as well, indicating the presence of more than one strain causing ergot in the U.S. A DNA-based tool for the detection of the ergot pathogen was developed as well.
Technical Abstract: Genetic variability within a global collection of the sorghum ergot pathogen Claviceps africana was analyzed using DNA sequence analysis, RAM analysis, and AFLP analysis. DNA sequence analysis of the beta-tubulin and elongation factor 1 alpha genes allowed distinct groupings of Claviceps species to be made, and PCR primers were designed for specific detection of C. africana and other species. AFLP analysis allowed assessment of intraspecific variation in C. africana. Strong associations were observed among Australian/Indian/Japanese isolates and U.S./Mexican/African isolates. Within individual populations including that present in the U.S., AFLP polymorphisms were observed, indicating the presence of multiple C. africana genotypes.