Phylogenetic analyses of the lotus root parasitic nematodes Hirschmanniella diversa and H. imamuri based on the 18S ribosomal RNA (rRNA) gene and 5.8S rRNA gene/internal transcribed spacer region

In this study, phylogenetic analysis was performed based on nearly full-length sequences of the 18S ribosomal RNA (rRNA) gene and 5.8S rRNA gene/internal transcribed spacer (ITS) region of the plant-parasitic nematodes Hirschmanniella diversa and H. imamuri and other related taxa. The analysis placed H. diversa and H. imamuri in Clade I with 3 known species, namely, H. santarosae, H. pomponiensis and H. gracilis. Among the hosts of these nematodes, families Poaceae and Typhaceae were consistent among H. diversa and the 2 species in Clade I. Phylogenetic analysis based on the 5.8S rRNA gene/ITS region suggests that Hirschmanniella spp. in all clades can parasitize family Poaceae. Interestingly, although H. imamuri and H. oryzae are both rice (Oryza sativa) root-parasitic nematodes, they were placed in Clade I and Clade III, respectively, indicating that they have different evolutionary histories.