Prochloron (from the Greek pro (before) and the Greek chloros (green) ) is a unicellular oxygenic photosynthetic prokaryote commonly found as an extracellular symbiont on coral reefs, particularly in didemnid ascidians (sea squirts). Part of the phylum cyanobacteria, it was theorized (endosymbiotic theory) that Prochloron is a predecessor of the photosynthetic components, chloroplasts, found in photosynthetic eukaryotic cells. However this theory is largely refuted by phylogenetic studies which indicate Prochloron is not on the same line of descent that lead to chloroplast-containing algae and land plants (La Roche et al., 1996).
Prochloron was discovered in 1975 by Ralph A. Lewin of the Scripps Institution of Oceanography. Prochloron is one of three known prochlorophytes, cyanobacteria that contain both chlorophyll a and b bound to a special light-harvesting protein (La Roche et al., 1996)
The only taxonomically valid species is P. didemni.
- La Roche, J., van der Staay, G. W. M., Ducret, A.,Aebersold, R., Li, R., Golden, S. S., Hiller, R. G., Wrench, P. M., Larkum, A.W. D. and Green, B. R.. 1996 Independent evolution of the prochlorophyte and green plant chlorophyll a/b light-harvesting proteins. Proc. Natl. Acad. Sci. (US) 93, 15244-48.
- Guiry, M.D.; Guiry, G.M. (2008). "Prochloron". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 2009-02-21.
- Waterbury, John, et al. Little Things Matter A Lot. Oceanus Magazine. 2004, 43(2).