Molecular Phylogenetic Analysis of Japanese Miscanthus (Poaceae)

Abstract

Miscanthus (Poaceae) comprises about 20 species, of which seven species and two forms occur in Japan. There is controversy whether M. condensatus is a separate species or a variety or subspecies of M. sinensis. To determine its taxonomic status, we conducted a molecular phylogenetic analysis using DNA sequences of the atpB-rbcL, psbC-trnS(UGA), rpl20-rps12, trnL(UAA)-trnF(GAA), trnS(GGA)- trnT(UGU), and nuclear ITS regions, and the Adh1 gene from 31 samples of the seven Japanese species of Miscanthus. The neighbor-joining (NJ) tree based on the cpDNA sequences shows that M. condensatus and M. sinensis share two haplotypes, and that the nuclear ITS and Adh1 sequences of the two species are identical, making it difficult to distinguish M. condensatus from M. sinensis based on DNA sequences. The evidence indicates that hybridization between the two species has proceeded rapidly, or that M. condensatus is derived from a diverging lineage of M. sinensis. The status of M. condensatus remains controversial, but our findings support provisionally treating M. condensatus as the infraspecific taxon, M. sinensis var. condensatus.