Internal transcribed spacer sequence-based phylogeny and polymerase chain reaction-restriction fragment length polymorphism differentiation of Tilletia walkeri and T-indica

A polymerase chain reaction-restriction fragment length polymorphism assay to distinguish Tilleita walkeri, a rye grass bunt fungus that occurs in the southeastern United States and Oregon, from T indica, the Karnal bunt fung us, is described. The internal transcribed spacer (ITS) region of the ribos omal DNA repeat unit was amplified and sequenced for isolates of T. indica, T. walkeri, T. horrida, and a number of other taxa in the genus Tilletia. A unique restriction digest site in the ITS1 region of T. walkeri was ident ified that distinguishes it from the other taxa in the genus. Phylogenetic analysis of the taxa based on ITS sequence data revealed a close relationsh ip between T. indices and T. walkeri, but more distant relationships betwee n these two species and other morphologically similar taxa.