Problems and paradigms
How do endosymbionts become organelles? Understanding early events in plastid evolution
Article first published online: 16 NOV 2007
Copyright © 2007 Wiley Periodicals, Inc.
Volume 29, Issue 12, pages 1239–1246, December 2007
How to Cite
Bhattacharya, D., Archibald, J. M., Weber, A. P.M. and Reyes-Prieto, A. (2007), How do endosymbionts become organelles? Understanding early events in plastid evolution. Bioessays, 29: 1239–1246. doi: 10.1002/bies.20671
- Issue published online: 16 NOV 2007
- Article first published online: 16 NOV 2007
- A.R.P. and D.B. acknowledge generous continuing support from the U.S. National Science Foundation of our endosymbiosis and algal research in grants awarded to D.B. (MCB 0236631, EF 0431117, EF 0625440) and to NASA (NNG04GM17G) for supporting the work on endosymbiotic gene transfer. A.P.M.W. acknowledges support from the National Science Foundation (EF 0332882). J.M.A acknowledges support from the Natural Sciences and Engineering Research Council of Canada and the Canadian Institutes for Health Research
What factors drove the transformation of the cyanobacterial progenitor of plastids (e.g. chloroplasts) from endosymbiont to bona fide organelle? This question lies at the heart of organelle genesis because, whereas intracellular endosymbionts are widespread in both unicellular and multicellular eukaryotes (e.g. rhizobial bacteria, Chlorella cells in ciliates, Buchnera in aphids), only two canonical eukaryotic organelles of endosymbiotic origin are recognized, the plastids of algae and plants and the mitochondrion. Emerging data on (1) the discovery of non-canonical plastid protein targeting, (2) the recent origin of a cyanobacterial-derived organelle in the filose amoeba Paulinella chromatophora, and (3) the extraordinarily reduced genomes of psyllid bacterial endosymbionts begin to blur the distinction between endosymbiont and organelle. Here we discuss the use of these terms in light of new data in order to highlight the unique aspects of plastids and mitochondria and underscore their central role in eukaryotic evolution. BioEssays 29:1239–1246, 2007. © 2007 Wiley Periodicals, Inc.