Molecular phylogenetic relationships among populations of Sagittaria aginashiMakino (Alismataceae) and endemic Chinese species

The aquatic plant Sagittaria aginashi, which is an endangered emergent species distributed in South Korea, Japan, and the Russian Far East, has an unclear phylogeny and genetic structure. Phylogenetic trees of Sagittariawere constructed based on one nuclear ribosomal DNA (nrDNA) region and on three chloroplast DNA (cpDNA) regions. S. aginashiwas included in a clade comprising three endemic Chinese Sagitarriaspecies characterized by the presence of small tubercles at the base of the axils. Furthermore, phylogenetic trees based on cpDNA sequences indicated that S. aginashiwas more closely related to S. tengtsungensisthan to two other species. S. aginashiexhibited little genetic variation, suggesting that this species had rapidly spread in these areas. With regard to factors associated with the rapid spread, we considered that multiple dispersal methods were involved, namely hydrochory viatubercles, endozoochorous long-distance dispersal, and anthropogenic impacts of rice farming on S. aginashidispersal.