Molecular phylogenetic analysis among bryophytes and tracheophytes based on combined data of plastid coded genes and the 18S rRNA gene.

The basal relationship of bryophytes and tracheophytes is problematic in land plant phylogeny. In addition to cladistic analyses of morphological data, molecular phylogenetic analyses of the nuclear small-subunit ribosomal RNA gene and the plastic gene rbcL have been performed, but no confident conclusions have been reached. Using the maximum-likelihood (ML) method, we analyzed 4,563 bp of aligned sequences from plastid protein-coding genes and 1,680 bp from the nuclear 18S rRNA gene. In the ML tree of deduced amino acid sequences of the plastid genes, hornworts were basal among the land plants, while mosses and liverworts each formed a clade and were sister to each other. Total-evidence evaluation of rRNA data and plastid protein-coding genes by TOTALML had an almost identical result.