Ribosomal DNA-ITS sequence polymorphism in the sugarcane rust, Puccinia kuehnii

Abstract

The two highly divergent ITS types previously observed in isolates of Puccinia kuehnii were amplified from the same isolates through the use of ITS type-specific primers for PCR and are therefore considered as polymorphisms of ITS regions within the species. Although homology of sequences of one of the ITS types with other Puccinia species was of expected levels, significantly high homology of sequences of the other type with those of Cronartium members indicates that abnormal genetic events led to the occurrence of these polymorphic regions. These results indicate that ITS gene tree phylogeny may not reflect true species phylogeny in this group of rust fungi. Rather, D1/D2 region tree phylogeny, which was concordant with the differences in morphology with and among related rusts, more correctly reflects phylogenetic relationships of sugarcane and related grass rusts.