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Diversification of DNA sequences in the symbiotic genome of Rhizobium etli.
J Bacteriol. 2005 Nov; 187(21):7185-92.JB

Abstract

Bacteria of the genus Rhizobium and related genera establish nitrogen-fixing symbioses with the roots of leguminous plants. The genetic elements that participate in the symbiotic process are usually compartmentalized in the genome, either as independent replicons (symbiotic plasmids) or as symbiotic regions or islands in the chromosome. The complete nucleotide sequence of the symbiotic plasmid of Rhizobium etli model strain CFN42, symbiont of the common bean plant, has been reported. To better understand the basis of DNA sequence diversification of this symbiotic compartment, we analyzed the distribution of single-nucleotide polymorphisms in homologous regions from different Rhizobium etli strains. The distribution of polymorphisms is highly asymmetric in each of the different strains, alternating regions containing very few changes with regions harboring an elevated number of substitutions. The regions showing high polymorphism do not correspond with discrete genetic elements and are not the same in the different strains, indicating that they are not hypervariable regions of functional genes. Most interesting, some highly polymorphic regions share exactly the same nucleotide substitutions in more than one strain. Furthermore, in different regions of the symbiotic compartment, different sets of strains share the same substitutions. The data indicate that the majority of nucleotide substitutions are spread in the population by recombination and that the contribution of new mutations to polymorphism is relatively low. We propose that the horizontal transfer of homologous DNA segments among closely related organisms is a major source of genomic diversification.

Authors+Show Affiliations

Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Ap. Postal 565-A, Cuernavaca, Morelos, México.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

16237002

Citation

Flores, Margarita, et al. "Diversification of DNA Sequences in the Symbiotic Genome of Rhizobium Etli." Journal of Bacteriology, vol. 187, no. 21, 2005, pp. 7185-92.
Flores M, Morales L, Avila A, et al. Diversification of DNA sequences in the symbiotic genome of Rhizobium etli. J Bacteriol. 2005;187(21):7185-92.
Flores, M., Morales, L., Avila, A., González, V., Bustos, P., García, D., Mora, Y., Guo, X., Collado-Vides, J., Piñero, D., Dávila, G., Mora, J., & Palacios, R. (2005). Diversification of DNA sequences in the symbiotic genome of Rhizobium etli. Journal of Bacteriology, 187(21), 7185-92.
Flores M, et al. Diversification of DNA Sequences in the Symbiotic Genome of Rhizobium Etli. J Bacteriol. 2005;187(21):7185-92. PubMed PMID: 16237002.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Diversification of DNA sequences in the symbiotic genome of Rhizobium etli. AU - Flores,Margarita, AU - Morales,Lucia, AU - Avila,Agustín, AU - González,Víctor, AU - Bustos,Patricia, AU - García,Delfino, AU - Mora,Yolanda, AU - Guo,Xianwu, AU - Collado-Vides,Julio, AU - Piñero,Daniel, AU - Dávila,Guillermo, AU - Mora,Jaime, AU - Palacios,Rafael, PY - 2005/10/21/pubmed PY - 2005/12/13/medline PY - 2005/10/21/entrez SP - 7185 EP - 92 JF - Journal of bacteriology JO - J. Bacteriol. VL - 187 IS - 21 N2 - Bacteria of the genus Rhizobium and related genera establish nitrogen-fixing symbioses with the roots of leguminous plants. The genetic elements that participate in the symbiotic process are usually compartmentalized in the genome, either as independent replicons (symbiotic plasmids) or as symbiotic regions or islands in the chromosome. The complete nucleotide sequence of the symbiotic plasmid of Rhizobium etli model strain CFN42, symbiont of the common bean plant, has been reported. To better understand the basis of DNA sequence diversification of this symbiotic compartment, we analyzed the distribution of single-nucleotide polymorphisms in homologous regions from different Rhizobium etli strains. The distribution of polymorphisms is highly asymmetric in each of the different strains, alternating regions containing very few changes with regions harboring an elevated number of substitutions. The regions showing high polymorphism do not correspond with discrete genetic elements and are not the same in the different strains, indicating that they are not hypervariable regions of functional genes. Most interesting, some highly polymorphic regions share exactly the same nucleotide substitutions in more than one strain. Furthermore, in different regions of the symbiotic compartment, different sets of strains share the same substitutions. The data indicate that the majority of nucleotide substitutions are spread in the population by recombination and that the contribution of new mutations to polymorphism is relatively low. We propose that the horizontal transfer of homologous DNA segments among closely related organisms is a major source of genomic diversification. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/16237002/Diversification_of_DNA_sequences_in_the_symbiotic_genome_of_Rhizobium_etli_ L2 - http://jb.asm.org/cgi/pmidlookup?view=long&pmid=16237002 DB - PRIME DP - Unbound Medicine ER -