Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/28/2002
Publication Date: 11/14/2002
Citation: Tooley, P.W., Goley, E.D., Carras, M. M., Oneill, N.R. AFLP comparisons among claviceps africana isolates from the U.S., Mexico, Africa, Australia, India, and Japan. Plant Disease. 86:1247-1252. 2002. Interpretive Summary: Eighty-seven different strains of the fungus causing ergot disease on sorghum were analyzed genetically using a DNA based method called amplified fragment length polymorphism (AFLP). A large amount of diversity was observed among ergot strains from around the world, but the strains were found to fall into two groups. One group consisted of strains from Australia, India, and Japan and the other consisted of strains from the U.S., Mexico, and Africa. Strains within groups were between 75% and 100% similar to one another, but the two groups were only about 70% similar overall. The groups found seem to follow routes of trade and movement of sorghum seed. The results indicate that Africa may have been the source of ergot found in the Americas since 1996.
Technical Abstract: Eighty-seven isolates of the sorghum ergot pathogen, C. africana, from diverse geographic locations were analyzed using four different AFLP primer combinations to determine genetic relationships among isolates. Most isolates showed unique AFLP types, indicating that much genetic variation is present within C. africana. Two major groupings of isolates were found, with about 70% similarity between the groups. One group consisted of Australian, Indian, and Japanese isolates and the other of US, Mexican, and African isolates. In spite of overall high levels of genetic diversity observed in C. africana, isolates within the two major groups were between 75% and 100% similar. The data suggest that associations of C. africana isolates from worldwide sources could be the result of intercontinental trade and/or movement of seed. Results indicate that Africa was the likely source of C. africana that became established in the Americas from 1996 to the present.