MOLECULAR RELATIONSHIPS AMONG VARIETIES OF THE TILLETIA-FUSCA (T-BROMI) COMPLEX AND RELATED SPECIES

Twenty-six isolates representing six morphologically similar taxa of T illetia occurring in the western U.S.A. were compared using randomly a mplified polymorphic DNA (RAPD) markers and restriction fragment lengt h polymorphisms (RFLP) of the 5.8 s rDNA and flanking ITS regions. Two distinct clusters were separated in the dendrogram based on the RAPD analysis. One cluster contained isolates of T. controversa, Apera inte rrupta-infecting isolates of a potentially new species of Tilletia, an d isolates of the Bromus-infecting varieties bromi-tectorium and guyot iana of the T. fusca (= T. bromi) complex. The second cluster containe d Vulpia-infecting isolates of T. fusca var. fusca. The separation of the Bromus-infecting varieties bromi-tectorum and guyotiana correspond ing to host specificity shown in previous studies. The presence of gen etically distinct populations of T. fusca var. occurring on V. microst achys and V. octoflora is indicated by RAPD and RFLP analyses. Species status of T. togwatii, a bunt infecting Poa reflexa that was previous ly removed from the T. fusca complex, is also supported by RAPD and RF LP analyses.