Phylogenetic relationships between chlorophytes, chrysophytes, and oomycetes.

The phylogenetic relationships among the chlorophyte Chlamydomonas reinhardtii, the chrysophyte Ochromonas danica, and the oomycete Achyla bisexualis were explored by comparing the sequences of their small-subunit ribosomal RNA coding regions. Comparisons of similarity values or inspection of phylogenetic trees constructed by distance matrix methods reveal a very close relationship between oomycetes and chrysophytes. The separation of chrysophytes from chlorophytes is comparable to that of plants from animals, and both separations are far antedated by the divergence of a number of other protist groups.