Phylogenetic relationships of four Puccinia species parasitic on Artemisia in Japan

Puccinia dioicae var. micropuncta and P. caricisstipatae complete their life cycle by host-alternating between Artemisia (spermogonial-aecial stage) and Carex (uredinial-telial stage). These species are suggested to be biologically distinct by inoculation experiments and field observations. Two additional Puccinia ferruginosa and P. artemisiae-keiskeanae produce only telial stage on Artemisia. Similarities in the teliospore morphology and host relationship of the four Puccinia species suggest their close phylogenetic relationship. Nucleotide sequences of D1/D2 region and ITS2 regions with partial 5.8 S rDNA were analyzed to depict possible phylogenetic relationships among the four Puccinia species. In D1/D2 analysis, both macrocyclic and microcyclic species were closely positioned in one clade, not permitting resolution of the phylogenetic relationship between the species. The DNA sequence of ITS2 including partial 5.8 S rDNA was sufficiently variable to separate two macrocyclic species and P. artemisiaekeiskeanae; however, confident resolution of phylogenetic relationships of the three species was not possible. Nevertheless, the analysis suggested the derivation of P. artemisiae-keiskeanae from a macrocyclic, heteroecious ancestor that is most likely to be an ancestor of both P. caricisstipatae and P. dioicae var. micropuncta. In contrast, three isolates of morphologically identifiable P. ferruginosa were variously positioned in the phylogenetic tree, suggesting that P. ferruginosa is not monophyletic.