Genetic variability among isolates of Tilletia barclayana, T-indica and allied species

Tilletia barclayana, T. indica, T. rugispora and T. boutelouae are a group of floret-infecting smuts characterized by densely tuberculate teliospores. A morphologically similar smut infecting Lolium multiflorum was discovered in Oregon and the southeastern USA in 1996, although herbarium records sho w a similar smut on L. perenne has been present in Australia for at least t hirty years. Based on PCR-RFLP analysis of the rDNA and RAPD analysis, the U.S. ryegrass bunt is most similar to T. indica, but the relatively low sim ilarity (ca 25%) in the RAPD analysis does not support conspecificity of th e two taxa. Both RAPD and PCR-RFLP analyses suggest that T. barclayana comp rises at least two distinct taxa. One cluster corresponds to the rice-infec ting isolates, and the other to isolates infecting species of Panicum and P aspalum. Tilletia boutelouae and T. rugispora are supported as species dist inct from T. barclayana and T. indica based on both RAPD and PCR-RFLP analy ses.