Algal Chloroplasts


A great diversity of chloroplasts is found amongst the various algal groups. This diversity is the result of an intriguing evolutionary process that involved the acquisition of chloroplasts by different eukaryotic organisms.

Keywords: algae; chloroplast; plastid; protein targeting; organelle genome

Figure 1.

The evolution of chloroplasts by endosymbiosis. The primary chloroplasts arose through the capture and retention of a cyanobacterium by a phagotrophic eukaryote. Subsequent gene loss and transfer to the nucleus (arrowed) resulted in the evolution of the chloroplast organelle. This organelle spread to other eukaryotes by secondary endosymbiotic events in which eukaryotic algae were themselves engulfed. In two phyla the endosymbiont nucleus remains as a vestigial structure, the nucleomorph.

Figure 2.

Biolistic transformation of the chloroplast. The genetic engineering of the chloroplast genome can be achieved using the biolistic process in which DNA is delivered into the organelle compartment using a particle gun. The DNA is coated onto gold microparticles that are fired at the target cells or tissue. Recombination results in the integration of the DNA into the genome. The bottom panel illustrates the disruption of a chloroplast gene using a selectable marker conferring spectinomycin (Spc) resistance (Rochaix, ).

Figure 3.

Protein targeting into the chloroplast. In primary plastids, proteins synthesized in the cytosol are transported across the outer and inner membranes by a translocon complex (blue) that recognizes the transit peptide. This peptide is then removed by a stromal peptidase. In complex plastids, an additional peptide signal directs the protein across the outermost membrane as it is being translated on membrane‐bound ribosomes. This signal peptide is cleaved by a signal peptidase. How proteins cross the inner membrane of the CER is not known.



Köhler S, Delwiche CF, Denny PW et al. (1997) A plastid of probable green algal origin in apicomplexan parasites. Science 275: 1485–1489.

Kroth P and Strotmann H (1999) Diatom plastids: secondary endocytobiosis, plastid genome and protein import. Physiologia Plantarum 107: 136–141.

McFadden GI, Gilson PR, Douglas SE et al. (1997) Bosai genomics: sequencing the smallest eukaryotic genomes. Trends in Genetics 13: 46–49.

Mujer CV, Andrews DL, Manhart JR, Pierce SK and Rumpho ME (1996) Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica. Proceedings of the National Academy of Science of the USA 93: 12333–12338.

Race HL, Herrmann RG and Martin W (1999) Why have organelles retained genomes? Trends in Genetics 15: 364–370.

Reumann S and Keegstra K (1999) The endosymbiotic origin of the protein import machinery of chloroplastic envelope membranes. Trends in Plant Sciences 4: 302–307.

Rochaix JD (1997) Chloroplast reverse genetics: new insights into the function of plastid genes. Trends in Plant Sciences 2: 419–425.

Sulli C and Schwartzbach SD (1996) A soluble protein is imported into Euglena chloroplasts as a membrane‐bound precursor. Plant Cell 8: 43–53.

Striepen B (2001) T. gondii parasites expressing green fluorescent protein fusion. [∼striepen/gfp.html].

Tomitani A, Okada K, Miyashita H et al. (1999) Chlorophyll b and phycobilins in the common ancestor of cyanobacteria and chloroplasts. Nature 400: 159–162.

Zhang Z, Green BR and Cavalier‐Smith T (1999) Single gene circles in dinoflagellate chloroplast genomes. Nature 400: 155–159.

Further Reading

Bhattacharya D (1997) Origins of Algae and their Plastids. Vienna: Springer‐Verlag.

Delwiche CF (1999) Tracing the thread of plastid diversity through the tapestry of life. American Naturalist 154: S164–S177.

Martin W, Stoebe B, Goremykin V et al. (1998) Gene transfer to the nucleus and the evolution of chloroplasts. Nature 393: 162–165.

McFadden GI and Waller RF (1997) Plastids in parasites of humans. BioEssays 19: 1033–1040.

Palmer JD and Delwiche CF (1996) Second‐hand chloroplasts and the case of the disappearing nucleus. Proceedings of the National Academy of Sciences of the USA 93: 7432–7435.

Stern DB, Higgs DC and Yang J (1997) Transcription and translation in chloroplasts. Trends in Plant Sciences 2: 308–315.

Sze P (1998) A Biology of the Algae, 3rd edn. New York: McGraw‐Hill.

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How to Cite close
Purton, Saul(Jul 2001) Algal Chloroplasts. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0000316]