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Genomics and chloroplast evolution: what did cyanobacteria do for plants?

Raven JA, Allen JF - Genome Biol. (2003)

Bottom Line: The complete genome sequences of cyanobacteria and of the higher plant Arabidopsis thaliana leave no doubt that the plant chloroplast originated, through endosymbiosis, from a cyanobacterium.But the genomic legacy of cyanobacterial ancestry extends far beyond the chloroplast itself, and persists in organisms that have lost chloroplasts completely.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Environmental and Applied Biology, University of Dundee, Dundee DD1 4HN, UK. j.a.raven@dundee.ac.uk

ABSTRACT
The complete genome sequences of cyanobacteria and of the higher plant Arabidopsis thaliana leave no doubt that the plant chloroplast originated, through endosymbiosis, from a cyanobacterium. But the genomic legacy of cyanobacterial ancestry extends far beyond the chloroplast itself, and persists in organisms that have lost chloroplasts completely.

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A schematic outline of the acquisition, reduction, and loss of genomes and compartments during evolution. Black arrows indicate evolutionary pathways; white arrows indicate endosymbiotic events in the host cell. Endosymbiotic event 1 occurred at the origin of eukaryotes. The proteobacterial endosymbiont gave rise to mitochondria (the smaller organelles in the bottom part of the diagram). Endosymbiotic event 2 occurred at the origin of plastid-containing cells. Endosymbiotic event 3 represents the secondary and higher-order endosymbioses giving rise to numerous algal phyla, as well as apicomplexans (such as Plasmodium) which have residual plastids, and to trypanosomes, which have no plastid at all. Black, filled circles indicate nuclei or nucleomorphs; ellipses within organelles indicate bacterially derived genomes, which may be reduced or lost completely. More than one kind of host cell and of endosymbiont is involved in the secondary, and in the higher-order, symbioses. The genome of the Archaebacterium is not represented in the diagram.
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Figure 1: A schematic outline of the acquisition, reduction, and loss of genomes and compartments during evolution. Black arrows indicate evolutionary pathways; white arrows indicate endosymbiotic events in the host cell. Endosymbiotic event 1 occurred at the origin of eukaryotes. The proteobacterial endosymbiont gave rise to mitochondria (the smaller organelles in the bottom part of the diagram). Endosymbiotic event 2 occurred at the origin of plastid-containing cells. Endosymbiotic event 3 represents the secondary and higher-order endosymbioses giving rise to numerous algal phyla, as well as apicomplexans (such as Plasmodium) which have residual plastids, and to trypanosomes, which have no plastid at all. Black, filled circles indicate nuclei or nucleomorphs; ellipses within organelles indicate bacterially derived genomes, which may be reduced or lost completely. More than one kind of host cell and of endosymbiont is involved in the secondary, and in the higher-order, symbioses. The genome of the Archaebacterium is not represented in the diagram.

Mentions: The work of Brinkman et al. [8] re-examines the processes that have led to the high proportion of proteins of a bacterial human pathogen, Chlamydia, that are similar to those of plants. This similarity was formerly attributed to horizontal gene transfer from plants, or plant-like host organisms, to the bacterium. Brinkman et al. [8] point out that such gene transfer is unlikely since all extant Chlamydiaceae are obligate intracellular parasites of animals. Instead, the analysis by Brinkman et al. [8] shows that the majority of the plant-like genes in Chlamydia are, in plant cells, targeted to the chloroplast. But the conclusion that this targeting of proteins to chloroplasts is necessarily a function of their origin from a plastid ancestor is not always sound. Furthermore, Martin et al. [6] did not find much similarity between Chlamydia and Arabidopsis (see Figure 1 in [6]). Clearly, further investigation is needed.


Genomics and chloroplast evolution: what did cyanobacteria do for plants?

Raven JA, Allen JF - Genome Biol. (2003)

A schematic outline of the acquisition, reduction, and loss of genomes and compartments during evolution. Black arrows indicate evolutionary pathways; white arrows indicate endosymbiotic events in the host cell. Endosymbiotic event 1 occurred at the origin of eukaryotes. The proteobacterial endosymbiont gave rise to mitochondria (the smaller organelles in the bottom part of the diagram). Endosymbiotic event 2 occurred at the origin of plastid-containing cells. Endosymbiotic event 3 represents the secondary and higher-order endosymbioses giving rise to numerous algal phyla, as well as apicomplexans (such as Plasmodium) which have residual plastids, and to trypanosomes, which have no plastid at all. Black, filled circles indicate nuclei or nucleomorphs; ellipses within organelles indicate bacterially derived genomes, which may be reduced or lost completely. More than one kind of host cell and of endosymbiont is involved in the secondary, and in the higher-order, symbioses. The genome of the Archaebacterium is not represented in the diagram.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
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Figure 1: A schematic outline of the acquisition, reduction, and loss of genomes and compartments during evolution. Black arrows indicate evolutionary pathways; white arrows indicate endosymbiotic events in the host cell. Endosymbiotic event 1 occurred at the origin of eukaryotes. The proteobacterial endosymbiont gave rise to mitochondria (the smaller organelles in the bottom part of the diagram). Endosymbiotic event 2 occurred at the origin of plastid-containing cells. Endosymbiotic event 3 represents the secondary and higher-order endosymbioses giving rise to numerous algal phyla, as well as apicomplexans (such as Plasmodium) which have residual plastids, and to trypanosomes, which have no plastid at all. Black, filled circles indicate nuclei or nucleomorphs; ellipses within organelles indicate bacterially derived genomes, which may be reduced or lost completely. More than one kind of host cell and of endosymbiont is involved in the secondary, and in the higher-order, symbioses. The genome of the Archaebacterium is not represented in the diagram.
Mentions: The work of Brinkman et al. [8] re-examines the processes that have led to the high proportion of proteins of a bacterial human pathogen, Chlamydia, that are similar to those of plants. This similarity was formerly attributed to horizontal gene transfer from plants, or plant-like host organisms, to the bacterium. Brinkman et al. [8] point out that such gene transfer is unlikely since all extant Chlamydiaceae are obligate intracellular parasites of animals. Instead, the analysis by Brinkman et al. [8] shows that the majority of the plant-like genes in Chlamydia are, in plant cells, targeted to the chloroplast. But the conclusion that this targeting of proteins to chloroplasts is necessarily a function of their origin from a plastid ancestor is not always sound. Furthermore, Martin et al. [6] did not find much similarity between Chlamydia and Arabidopsis (see Figure 1 in [6]). Clearly, further investigation is needed.

Bottom Line: The complete genome sequences of cyanobacteria and of the higher plant Arabidopsis thaliana leave no doubt that the plant chloroplast originated, through endosymbiosis, from a cyanobacterium.But the genomic legacy of cyanobacterial ancestry extends far beyond the chloroplast itself, and persists in organisms that have lost chloroplasts completely.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Environmental and Applied Biology, University of Dundee, Dundee DD1 4HN, UK. j.a.raven@dundee.ac.uk

ABSTRACT
The complete genome sequences of cyanobacteria and of the higher plant Arabidopsis thaliana leave no doubt that the plant chloroplast originated, through endosymbiosis, from a cyanobacterium. But the genomic legacy of cyanobacterial ancestry extends far beyond the chloroplast itself, and persists in organisms that have lost chloroplasts completely.

Show MeSH