Molecular diversity and phylogeny reconstruction of genus Colobanthus (Caryophyllaceae) based on mitochondrial gene sequences

Mitochondrial genomes become an interesting object of evolutionary and systematic study both for animals and plants, including angiosperms. Although the framework of the angiosperm phylogeny was built on the information derived from chloroplast and nuclear genes also mitochondrial sequences revealed their usefulness in solving the phylogenetic issues at different levels of plant systematics. Here we report for the first time complete sequences of 26 protein-coding genes of eight Colobanthus species (Caryophyllaceae). 23 of them represented core mitochondrial genes, which are directly associated with the primarily function of that organelle, remaining three genes represented facultative set of mitochondrial genes. Comparative analysis of the identified genes revealed generally high degree of sequence conservation. Ka/Ks ratio was < 1 for most of the genes which indicated purifying selection. Only for rps12 Ka/Ks > 1 in all studied species suggesting positive selection. We identified 172-190 potential RNA editing sites in genes of studied species which is lower than in most angiosperms, but similar to Silene noctiflora (Caryophyllaceae). The reconstructed phylogeny based on mitochondrial genes was consistent with taxonomic position of studied species showing the separate character of family Caryophyllaceae and close relationships between all studied Colobanthus species, with C. lycopodioides shearing the less similarity.