Phylogenetic analysis of Gaeumannomyces graminis varieties based on sequence insertions in the small subunit rDNA

Gaeumanoumyces graminis (Gg) varieties (tritici, avenae and graminis) were found to possess sequence insertions in the middle region of the small subunit ribosomal DNA. The sequence insertions were used to distinguish Gg isolates from North America obtained from wheat, creeping bentgrass and St. Augustinegrass and to resolve their phylogenetic relationship. Based on the alignment of sequence insertions, Gg isolates were divided into two sets: set I contained all isolates of Ggt; Gga; and Ggg isolates WF 9124, WF 9238, and WF 9463; while set II contained the other Ggg isolates that possessed insertion sequences with different lengths. Phylogenetic analysis of sequence insertions from set I shows that Ggt are more closely related to Gga that is supported by bootstrap 85%. Ggg isolates did not form a distinct group and appeared mixed between the well supported Ggt and Gga groups. Parsimony analysis of Ggg set II insertions revealed a distinct clade consisting of three monophyletic groups.