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Plant-Bacteria Association and Symbiosis: Are There Common Genomic Traits in Alphaproteobacteria?

Department of Evolutionary Biology, University of Florence, via Romana 17, 50125 Firenze, Italy
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Genes 2011, 2(4), 1017-1032;
Received: 29 September 2011 / Revised: 8 November 2011 / Accepted: 9 November 2011 / Published: 29 November 2011
(This article belongs to the Special Issue Bacterial Genomes and Their Evolution)
PDF [529 KB, uploaded 29 November 2011]


Alphaproteobacteria show a great versatility in adapting to a broad range of environments and lifestyles, with the association between bacteria and plants as one of the most intriguing, spanning from relatively unspecific nonsymbiotic association (as rhizospheric or endophytic strains) to the highly species-specific interaction of rhizobia. To shed some light on possible common genetic features in such a heterogeneous set of plant associations, the genomes of 92 Alphaproteobacteria strains were analyzed with a fuzzy orthologs-species detection approach. This showed that the different habitats and lifestyles of plant-associated bacteria (soil, plant colonizers, symbiont) are partially reflected by the trend to have larger genomes with respect to nonplant-associated species. A relatively large set of genes specific to symbiotic bacteria (73 orthologous groups) was found, with a remarkable presence of regulators, sugar transporters, metabolic enzymes, nodulation genes and several genes with unknown function that could be good candidates for further characterization. Interestingly, 15 orthologous groupspresent in all plant-associated bacteria (symbiotic and nonsymbiotic), but absent in nonplant-associated bacteria, were also found, whose functions were mainly related to regulation of gene expression and electron transport. Two of these orthologous groups were also detected in fully sequenced plant-associated Betaproteobacteria and Gammaproteobacteria. Overall these results lead us to hypothesize that plant-bacteria associations, though quite variable, are partially supported by a conserved set of unsuspected gene functions. View Full-Text
Keywords: bacterial genomes; plant; symbiosis bacterial genomes; plant; symbiosis
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Pini, F.; Galardini, M.; Bazzicalupo, M.; Mengoni, A. Plant-Bacteria Association and Symbiosis: Are There Common Genomic Traits in Alphaproteobacteria? Genes 2011, 2, 1017-1032.

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