title: Phylogeny of the quadriflagellate Volvocales (Chlorophyceae) based on chloroplast multigene sequences.
abstract: Since the phylogenetic relationships of the green plants (green algae and land plants) have been extensively studied using 18S ribosomal RNA sequences, change in the arrangement of basal bodies in flagellate cells is considered to be one of the major evolutionary events in the green plants. However, the phylogenetic relationships between biflagellate and quadriflagellate species within the Volvocales remain uncertain. This study examined the phylogeny of three genera of quadriflagellate Volvocales (Carteria, Pseudocarteria, and Hafniomonas) using concatenated sequences from three chloroplast genes. Using these multigene sequences, all three quadriflagellate genera were basal to other members (biflagellates) of the CW (clockwise) group (the Volvocales and their relatives, the Chlorophyceae) and formed three robust clades. Since the flagellar apparatuses of these three quadriflagellate lineages are diverse, including counter clockwise (CCW) and CW orientation of the basal bodies, the CW orientation of the basal bodies might have evolved from the CCW orientation in the ancestral quadriflagellate volvocalean algae, giving rise to the biflagellates, major members of the CW group.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. nozaki@biol.s.u-tokyo.ac.jp
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Nozaki
authors.forename: Osami
authors.initials: O
authors.lastname: Misumi
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
mesh_terms: D000460:Chlorophyta / Q000145:classification / Q000166:cytology / Q000235:genetics*; D025222:Chloroplast Proton-Translocating ATPases / Q000235:genetics; D018742:DNA, Chloroplast / Q000235:genetics*; D019143:Evolution, Molecular; D005407:Flagella / Q000648:ultrastructure; D045342:Light-Harvesting Protein Complexes / Q000235:genetics; D005810:Multigene Family; D045331:Photosystem I Protein Complex / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000235:genetics; D010802:Phylogeny; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics
chemical_list: D018742:DNA, Chloroplast; D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; C089909:photosystem I, psaB subunit; C070970:photosystem II, chlorophyll-binding protein, CP-47; D025222:Chloroplast Proton-Translocating ATPases; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase