PHYLOGENETIC RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM rbcL GENE SEQUENCE DATA

Abstract

The chloroplast‐encoded large subunit of the ribulose‐1, 5‐bisphosphate carboxylase / oxygenase (rbcL) gene was sequenced from 20 species of the colonial Volvocales (the Volvacaceae, Goniaceae, and Tetrabaenaceae) in order to elucidate phylogenetic relationships within the colonial Volvocales. Eleven hundred twenty‐eight base pairs in the coding regions of the (rbcL) gene were analyzed by the neighbor‐joining (NJ) method using three kinds of distance estimations, as well as by the maximum parsimony (MP) method. A large group comprising all the anisogamous and oogamous volvocacean species was resolved in the MP tree as well as in the NJ trees based on overall and synonymous substitutions. In all the trees constructed, Basichlamys and Tetrabaena (Tetrabaenaceae) constituted a very robust phylogenetic group. Although not supported by high bootstrap values, the MP tree and the NJ tree based on nonsynonymous substitutions indicated that the Tetrabaenaceae is the sister group to the large group comprising the Volvocaceae and the Goniaceae. In addition, the present analysis strongly suggested that Pandorina and Astrephomene are monophyletic genera whereas Eudorina is nonmonophyletic. These results are essentially consistent with the results of the recent cladistic analyses of morphological data. However, the monophyly of the Volvocaceae previously supported by four morphological synapomorphies is found only in the NJ tree based on nonsynonymous substitutions (with very low bootstrap values). The genus Volvox was clearly resolved as a polyphyletic group with V. rousseletii Pocock separated from other species of Volvox in the rbcL gene comparisons, although this genus represents a monophyletic group in the previous morphological analyses. Furthermore, none of the rbcL gene trees supported the monophyly of the Goniaceae; Astrephomene was placed in various phylogenetic positions.

A taxonomic study ofEudorina unicocca(Volvocaceae, Chlorophyceae) and related species, based on morphology and molecular phylogeny

“…The method for sequencing the chloroplast gene (rbcL) for the large subunit of RuBisCO of two strains of Y. unicocca (Hasu-1 and NIES-870), E. unicocca UTEX 1221 and two aplanosporic strains (TKI-C-2 and 990601-IE-5) was essentially identical to that described previously (Nozaki et al, 1995(Nozaki et al, , 1997(Nozaki et al, , 2000(Nozaki et al, , 2002. The region sequenced corresponded to rbcL positions 31-1159 in Chlorella vulgaris Beijerinck (Yoshinaga et al, 1988;Wakasuagi et al, 1997).…”

Identification of the Minus-Dominance Gene Ortholog in the Mating-Type Locus of Gonium pectorale

“…Nested RT-PCR using this cDNA yielded the partial fragment of GpMID; the primers used in the first PCR were the Seegene kit's 39-rapid amplification of the cDNA end (39-RACE) primer and dMT-dF3 (primers designed in this study are listed in Table 1); the primers used in the second PCR were dMT-dF3 and mt-R4 . The PCR reactions were carried out using TAKARA Taq polymerase (TAKARA, Osaka, Japan) using the cycling conditions described previously (Nozaki et al 1995). To determine the C terminus sequence of GpMID, 39-RACE was performed with the 39-RACE primer of the kit and GpMidF1.…”

Morphological and Genetic Variation in the Cosmopolitan Snow Alga Chloromonas nivalis (Volvocales, Chlorophyta) from Japanese Mountainous Area

“…Because it was unsuccessful to obtain rbcL gene sequences from zygotes of C. nivalis using previous published primers (Nozaki et al 1995(Nozaki et al , 1997 in the single-cell sequencing, specific primers newly designed (see Materials and methods) were used for single-cell sequencing of the zygotes. As a result, the partial sequences of rbcL gene (340-400 bp) were determined.…”