Use of RAPD Markers as a Diagnostic Tool for the Identificationof Fusarium solani Isolates that Cause Soybean Sudden Death Syndrome. Laurie A. Achenbach, Department of Microbiology, Southern Illinois University, Carbon-dale 62901. Jennifer Patrick, Department of Microbiology, Southern Illinois University, Carbon-dale 62901; and Lynn Gray, USDA/ARS and Department of Plant Pathology, University of Illinois, Urbana 61801;. Plant Dis. 80:1228-1232. Accepted for publication 11 July 1996. Copy right 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-1228.

Fusarium solani is the etiological agent of soybean sudden death syndrome (SDS). Random amplified polymorphic DNA (RAPD) analysis was used to differentiate isolates that cause SDS from those that do not. Greenhouse assays with a sand/cornmeal inoculum method were performed to assess virulence of the fungal isolates and the results were compared with the RAPD pattern analysis. The RAPD results exhibited 100% association with greenhouse virulence assay results. Amplification patterns generated by RAPD reactions were used to generate a phenogram depicting the genetically distinct nature of the cluster defined by the SDS isolates. This cluster was exclusive and distinct from F. solani f. sp. phaseoli isolates that do not cause SDS. Thus, the RAPD approach proved a sensitive and highly reliable method for quickly identifying fungal pathotypes that cause soybean SDS.