Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.)

BMC Genomics

Research Article

Ernesto Ormeño-Orrillo¹  Esperanza Martínez-Romero¹  Jesiane Stefânia Silva Batista²  Mariangela Hungria²  Andre Shigueyoshi Nakatani²  Pâmela Menna²  Ligia Maria Oliveira Chueire²  Ana Tereza Ribeiro Vasconcelos³  Marisa Fabiana Nicolás³  Luiz Gonzaga P Almeida³  Rangel Celso Souza³  Francisco Javier Ollero⁴  Manuel Megías⁴  Elisete Pains Rodrigues⁵ 

[1] Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico;Embrapa Soja, C. P. 231, 86001-970, Londrina, Paraná, Brazil;Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil;Universidad de Sevilla, Apdo Postal 874, 41080, Sevilla, Spain;Universidade Estadual de Londrina, Cx. Postal 60001, 86051-990, Londrina, Paraná, Brazil;

关键词: Nodulation;    Nitrogen fixation;    Plant-microbe interactions;    Antimicrobial resistance;   

DOI  :  10.1186/1471-2164-13-735

 received in 2012-09-05, accepted in 2012-12-15,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundRhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown.ResultsGenome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym) that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins.ConclusionsAvailability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.

【 授权许可】

CC BY   
© Ormeño-Orrillo et al.; licensee BioMed Central Ltd. 2012