The cyanobacteria constitute one of the main phyla within Bacteria, with more than 1500 species known. They are the sole prokaryotic group capable of carrying out oxygenic photosynthesis and their emergence was a major evolutionary event leading to the change in the atmosphere from anoxygenic to oxygenic. Cyanobacteria exhibit enormous diversity in terms of their morphology, physiology and differentiation characteristics. The phylogenetic trees based on 16S rRNA have been unable to resolve the branching orders or interrelationships among cyanobacteria. It is now well established that cyanobacteria, through endosymbiosis, have given rise to the plastids in eukaryotic cells. However, the questions as to which subgroup of cyanobacteria were the possible progenitors of plastids, or how plastids in different photosynthetic eukaryotes are related to each other, are presently not understood. The signature approach should prove very useful in understanding of these questions. A number of cyanobacterial-specific signatures, some of these are also present in the plastid homologs, are noted below. Additional signatures, distinctive of various cyanobacterial subgroups and their interrelationships will be posted in future.
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Selected References:
Gray, M. W.(1993) Origin and evolution of organelle genomes. Current.Opinion.in Genetics &.Development, 3: 884-890. [Abstract]
Gupta, R. S., Pereira, M., Chandrasekera, C. and Johari, V. (2003) Molecular Signatures in Protein Sequences that are Distinctive of Cyanobacterial and Plastid Homologs. Int. J. Syst. Evol. Microbiol. 53: 1833-1842. [Abstract]
Gupta, R. S. (2003) Evolutionary relationships among photosynthetic bacteria. Photosynthesis Res. 76: 173-183. [PDF]
Gupta, R. S. (2004) Evolutionary Relationship Among Photosynthetic Bacteria. Int. Congress of Photobiology, Jeju, Korea. [PDF of the Power Point presentation]
Margulis, L. Symbiosis in Cell Evolution.New York: W.H. Freeman and Company, 1993.
Palmer, J. D. and Delwiche, C. F. (1998) The origin and evolution of plastids and their genomes. In D. E. Sotis, P. E. Soltis, and J. J. Doyle (eds.), Molecular Systematics of Plants II DNA Sequencing, pp. 375-409, Kluwer Academic Publishers, Norwell, MA.
Wilmotte, A. and Herdman, M. (2001)Phylogenetic Relationships among the Cyanobacteria Based on 16S rRNA Sequences. In D. R. Boone and R. W. Castenholz (eds.), Bergey's Manual of Systematic Bacteriology, vol. 1, 2nd ed, pp. 487-493, Springer, New York.
Citation for this webpage:
Bacterial (Prokaryotic) Phylogeny Webpage (March 2006). http://www.bacterialphylogeny.com/index.html