Genetic relationships of pathogenic Typhula species assessed by RAPD, ITS-RFLP and ITS sequencing

Several species of Typhula cause diseases of cereals and grasses at low tem peratures. Taxonomic separation of T. phacorrhiza, T. incarnata and T. ishi kariensis was investigated using RAPD, ITS-RFLP and nucleotide sequencing o f the TTS region. Using 10 RAPD primers on genomic DNA or eight restriction enzymes on PCR-amplified ITS regions, banding patterns were generated for each of 19 isolates from five species or varieties. Polymorphisms were foun d between species and varieties, with fewer among isolates within species o r varieties. RAPD analysis suggested that T. ishikariensis var. idahoensis may be distinct from the other varieties (var. ishikariensis and var. canad ensis), although this was not supported by ITS-RFLP. To confirm relationshi ps, ITS nucleotides were obtained from single isolates of each of the five Typhula taxa, and sequence alignments were subjected to distance and parsim ony analysis. Although there were differences in branching between dendrogr ams derived from sequencing vs. RAPD or ITS-RFLP, sequence data supported t he distinction of the three main Typhula species, with the T. ishikariensis Varieties grouping together and showing differences at an infraspecific le vel. ITS sequence data also indicated the closer taxonomic affinity of Typh ula species to the agaricoid Tricholoma sejunctum compared to the clavarioi d Thelephora terrestris.