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Journal of Molecular Evolution

, Volume 45, Issue 6, pp 682–687 | Cite as

The Origin of Chlorarachniophyte Plastids, as Inferred from Phylogenetic Comparisons of Amino Acid Sequences of EF-Tu

  • Ken-ichiro  Ishida
  • Ying  Cao
  • Masami  Hasegawa
  • Norihiro  Okada
  • Yoshiaki  Hara

Abstract.

A molecular phylogenetic analysis of elongation factor Tu (EF-Tu) proteins from plastids was performed in an attempt to identify the origin of chlorarachniophyte plastids, which are considered to have evolved from the endosymbiont of a photosynthetic eukaryote. Partial sequences of the genes for plastid EF-Tu proteins (1,080–1,089 bp) were determined for three algae that contain chlorophyll b, namely, Gymnochlora stellata (Chlorarachniophyceae), Bryopsis maxima (Ulvophyceae), and Pyramimonas disomata (Prasinophyceae). The deduced amino acid sequences were used to construct phylogenetic trees of the plastid and bacterial EF-Tu proteins by the maximum likelihood, the maximum parsimony, and the neighbor joining methods.

The trees obtained in the present analysis suggest that all plastids that contain chlorophyll b are monophyletic and that the chlorarachniophyte plastids are closely related to those of the Ulvophyceae. The phylogenetic trees also suggest that euglenophyte plastids are closely related to prasinophycean plastids. The results indicate that the chlorarachniophyte plastids evolved from a green algal endosymbiont that was closely related to the Ulvophyceae and that at least two secondary endosymbiotic events have occurred in the lineage of algae with plastids that contain chlorophyll b.

Key words: Chlorarachniophyceae — Endosymbiosis — Origin of plastids — Elongation factor Tu — Protein phylogeny 

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Copyright information

© Springer-Verlag New York Inc. 1997

Authors and Affiliations

  • Ken-ichiro  Ishida
    • 1
  • Ying  Cao
    • 1
  • Masami  Hasegawa
    • 2
  • Norihiro  Okada
    • 1
  • Yoshiaki  Hara
    • 3
  1. 1.Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226, JapanJP
  2. 2.The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo 106, JapanJP
  3. 3.Department of Biology, Faculty of Science, Yamagata University, Kojirakawa, Yamagata 990, JapanJP

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