Plant Biol (Stuttg) 2004; 6(4): 447-453
DOI: 10.1055/s-2004-820888
Original Paper

Georg Thieme Verlag Stuttgart KG · New York

Phylogenetic Position of Endosymbiotic Green Algae in Paramecium bursaria Ehrenberg from Japan

R. Hoshina1 , S.-i. Kamako1 , N. Imamura1
  • 1Department of Bio Science and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu Shiga, Japan
Further Information

Publication History

Publication Date:
12 July 2004 (online)


Endosymbiotic green algae of Japanese Paramecium bursaria were phylogenetically analyzed based on DNA sequences from the ribosomal DNA operon (18S rDNA, ITS1, 5.8S rDNA, and ITS2). Phylogenetic trees constructed using 18S rDNA sequences showed that the symbionts belong to the Chlorella sensu stricto (Trebouxiophyceae) group. They are genetically closer to the C. vulgaris Beijerinck group than to C. kessleri Fott et Nováková as proposed previously. Branching order in C. vulgaris group was unresolved in 18S rDNA trees. Compared heterogeneities of 18S rDNA, ITS1, 5.8S r, and ITS2 among symbionts and two Chlorella species, indicated that the ITS2 region (and probably also ITS1) is better able to resolve phylogenetic problems in such closely related taxa. All six symbiotic sequences obtained here (approximately 4000-bp sequences of 18S rDNA, ITS1, 5.8S rDNA, and ITS2) were completely identical in each, strongly suggesting a common origin.


N. Imamura

Department of Bio Science and Biotechnology
Faculty of Science and Engineering
Ritsumeikan University

Noji Higashi 1-1-1

Kusatsu Shiga 525-8577



Section Editor: F. Salamini