Genetic characterization and distribution of mating type genes in Sclerotinia homoeocarpa populations
A. I. PUTMAN (1), I. Carbone (1), L. P. Tredway (1)
(1) North Carolina State University, Raleigh, NC, U.S.A.
Phytopathology 101:S147

Dollar spot, the most economically important disease of turfgrass worldwide, is caused by the filamentous ascomycete Sclerotinia homoeocarpa. The objective of this research is to characterize the genetics and distribution of mating type (MAT) genes in S. homoeocarpa populations. In an early draft genome assembly of S. homoeocarpa, the MAT locus was found to contain regions with similarity to the MAT1-1-1 genes, containing an alpha motif, and the MAT1-1-5 genes in the available genomes of S. sclerotiorum and Botrytis cinerea. Primers anchored in the flanking DNA lyase and cytoskeleton assembly genes were used to amplify and sequence the MAT1-2 idiomorph, which contained a high mobility group-box motif with similarity to MAT1-2-1 genes. The MAT locus in S. homoeocarpa is similar to that of B. cinerea with respect to gene orientation and the presence of a truncated portion of MAT1-2-1 flanking the MAT1-1 idiomorph. However, unlike B. cinerea, elements of the MAT1-2-3 gene and a deleted portion of MAT1-1-1 were not detected in the MAT1-2 idiomorph in S. homoeocarpa. In a limited survey, 55 of 121 isolates of S. homoeocarpa from North America and 3 of 49 isolates from Asia, Europe, and South America were determined to contain the MAT1-1 idiomorph. A multiplex PCR assay is currently being developed to rapidly screen worldwide populations of the pathogen. Data developed from this study will be useful in population studies of S. homoeocarpa.