Assessment of diversity in Claviceps africana and other Claviceps species by RAM and AFLP analyses

Genetic diversity among isolates of Claviceps africana, the sorghum ergot p athogen, and isolates of other Claviceps spp. causing ergot on sorghum or o ther hosts, was analyzed by random amplified microsatellite (RAM) and ampli fied fragment length polymorphism (AFLP) analyses. Of the RAM primer sets t ested, one revealed polymorphism in C. africana isolates, with Australian a nd Indian isolates possessing a unique fragment. AFLP analysis, in addition to clearly distinguishing Claviceps spp., revealed polymorphisms in C. afr icana. A group of isolates from the United States, Puerto Rico, and South A frica exhibited 95 to 100% similarity with one another. Several isolates fr om Isabela, Puerto Rico were 100% similar to an isolate from Texas, and ano ther isolate from Puerto Rico was identical with one from Nebraska. Austral ian and Indian isolates showed greater than 90% similarity with isolates fr om the United States., Puerto Rico, and South Africa. A number of polymorph isms existed in the United States group, indicating that the recently intro duced population contains multiple genotypes. Isolates of C. sorghicola, a newly described sorghum pathogen from Japan, were very distinct from other species via RAM and AFLP analyses, as were isolates from outgroups C. purpu rea and C.fusiformis. Both RAM and AFLP analysis will be useful in determin ing future patterns of intercontinental migration of the sorghum ergot path ogen, with the AFLP method showing greater ability to characterize levels o f intraspecific variation.