The Composite Genome of the Legume Symbiont
            <i>Sinorhizobium meliloti</i>

Galibert, Francis; Finan, Turlough M.; Long, Sharon R.; Pühler, Alfred; Abola, Pia; Ampe, Frédéric; Barloy-Hubler, Frédérique; Barnett, Melanie J.; Becker, Anke; Boistard, P.; Bothe, Gordana; Boutry, Marc; Bowser, Leah; Buhrmester, Jens; Cadieu, Édouard; Capela, Delphine; Chain, Patrick; Cowie, Alison; Davis, Ronald W.; Dreano, Stéphane; Federspiel, Nancy A.; Fisher, Robert F.; Gloux, Stéphanie; Godrie, Thérèse; Goffeau, André; Golding, Brian; Gouzy, Jérôme; Gurjal, Mani; Hernández-Lucas, Ismael; Hong, Andrea; Huizar, Lucas; Hyman, Richard W.; Jones, Ted; Kahn, Daniel; Kahn, Michael L.; Kalman, Sumner M.; Keating, David H.; Kiss, Ernö; Komp, Caridad; Lelaure, Valérie; Masuy, David; Palm, Curtis J.; Peck, Melicent C.; Pohl, Thomas; Portetelle, Daniel; Purnelle, Bénédicte; Ramsperger, Uwe; Surzycki, Raymond; Thébault, Patricia; Vandenbol, Micheline; Vorhölter, Frank-J.; Weidner, Stefan; Wells, Derek H.; Wong, Kim; Yeh, Kuo‐Chen; Batut, Jacques

doi:10.1126/science.1060966

Cited by 1,085 publications

(815 citation statements)

References 13 publications

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“…Rhizobial genomes are subdivided into genome regions specific for their life stages, with chromosomal loci expressed during free-living phases in the soil and symbiosis loci expressed inside of host cells [13,14]. Symbiosis loci required for host nodulation and nitrogen fixation are clustered onto large plasmids or genomic islands [15][16][17][18][19], that can be transferred among lineages, presumably via conjugation [20][21][22]. Non-nodulating rhizobia are also common [23,24], and these strains often lack some or all of the characterized symbiosis loci [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Epidemic Spread of Symbiotic and Non-Symbiotic Bradyrhizobium Genotypes Across California

et al. 2015

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The patterns and drivers of bacterial strain dominance remain poorly understood in natural populations. Here, we cultured 1292 Bradyrhizobium isolates from symbiotic root nodules and the soil root interface of the host plant Acmispon strigosus across a >840-km transect in California. To investigate epidemiology and the potential role of accessory loci as epidemic drivers, isolates were genotyped at two chromosomal loci and were assayed for presence or absence of accessory Bsymbiosis island^loci that encode capacity to form nodules on hosts. We found that Bradyrhizobium populations were very diverse but dominated by few haplotypeswith a single Bepidemic^haplotype constituting nearly 30 % of collected isolates and spreading nearly statewide. In many Bradyrhizobium lineages, we inferred presence and absence of the symbiosis island suggesting recurrent evolutionary gain and or loss of symbiotic capacity. We did not find statistical phylogenetic evidence that the symbiosis island acquisition promotes strain dominance and both symbiotic and nonsymbiotic strains exhibited population dominance and spatial spread. Our dataset reveals that a strikingly few Bradyrhizobium genotypes can rapidly spread to dominate a landscape and suggests that these epidemics are not driven by the acquisition of accessory loci as occurs in key human pathogens.

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Section: Introductionmentioning

confidence: 99%

Epidemic Spread of Symbiotic and Non-Symbiotic Bradyrhizobium Genotypes Across California

et al. 2015

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“…Although modABC homologues have been found in the genome sequence of symbiotic nitrogen fixers, such as Sinorhizobium meliloti (Galibert et al, 2001), M. loti (Kaneko et al, 2000) and B. japonicum (Kaneko et al, 2002), whether this is the only transporter for rhizobia and whether it operates in bacteroids remains to be seen. In this paper, we describe for the first time a symbiotic phenotype of rhizobia strains affected in the high-affinity Mo transporter ModABC.…”

Section: Effects Of Mod Mutations On Nitrogenase Activitymentioning

confidence: 99%

Functional characterization of the Bradyrhizobium japonicum modA and modB genes involved in molybdenum transport

et al. 2006

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A modABC gene cluster that encodes an ABC-type, high-affinity molybdate transporter from Bradyrhizobium japonicum has been isolated and characterized. B. japonicum modA and modB mutant strains were unable to grow aerobically or anaerobically with nitrate as nitrogen source or as respiratory substrate, respectively, and lacked nitrate reductase activity. The nitrogen-fixing ability of the mod mutants in symbiotic association with soybean plants grown in a Mo-deficient mineral solution was severely impaired. Addition of molybdate to the bacterial growth medium or to the plant mineral solution fully restored the wild-type phenotype. Because the amount of molybdate required for suppression of the mutant phenotype either under free-living or under symbiotic conditions was dependent on sulphate concentration, it is likely that a sulphate transporter is also involved in Mo uptake in B. japonicum. The promoter region of the modABC genes has been characterized by primer extension. Reverse transcription and expression of a transcriptional fusion, P modA -lacZ, was detected only in a B. japonicum modA mutant grown in a medium without molybdate supplementation. These findings indicate that transcription of the B. japonicum modABC genes is repressed by molybdate.

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“…Bacterial genetic and post-genomic approaches have demonstrated the critical role played by genes involved in the synthesis of nodulation factors (that is, nod genes) and surface polysaccharides (for example, exo or rkp genes) in providing signals for the recognition of S. meliloti and S. medicae by their host (Jones et al, 2007). While most functional studies have used S. meliloti as a model bacterium because the genome of the strain 1021 was available (Galibert et al, 2001), more studies in future might be performed on S. medicae now that the genome sequence of the strain WSM 419 has been released (Reeve et al, 2010), because this bacterium, isolated in Sardinia, is a better symbiont than S. meliloti 1021 for the model legume M. truncatula (Terpolilli et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Population genomics of Sinorhizobium medicae based on low-coverage sequencing of sympatric isolates

et al. 2011

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We investigated the genomic diversity of a local population of the symbiotic bacterium Sinorhizobium medicae, isolated from the roots of wild Medicago lupulina plants, in order to assess genomic diversity, to identify genomic regions influenced by duplication, deletion or strong selection, and to explore the composition of the pan-genome. Partial genome sequences of 12 isolates were obtained by Roche 454 shotgun sequencing (average 5.3 Mb per isolate) and compared with the published sequence of S. medicae WSM 419. Homologous recombination appears to have less impact on the polymorphism patterns of the chromosome than on the chromid pSMED01 and megaplasmid pSMED02. Moreover, pSMED02 is a hot spot of insertions and deletions. The whole chromosome is characterized by low sequence polymorphism, consistent with the high density of housekeeping genes. Similarly, the level of polymorphism of symbiosis genes (low) and of genes involved in polysaccharide synthesis (high) may reflect different selection. Finally, some isolates carry genes that may confer adaptations that S. medicae WSM 419 lacks, including homologues of genes encoding rhizobitoxine synthesis, iron uptake, response to autoinducer-2, and synthesis of distinct polysaccharides. The presence or absence of these genes was confirmed by PCR in each of these 12 isolates and a further 27 isolates from the same population. All isolates had rhizobitoxine genes, while the other genes were co-distributed, suggesting that they may be on the same mobile element. These results are discussed in relation to the ecology of Medicago symbionts and in the perspective of population genomics studies.

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The Composite Genome of the Legume Symbiont Sinorhizobium meliloti

Cited by 1,085 publications

References 13 publications

Epidemic Spread of Symbiotic and Non-Symbiotic Bradyrhizobium Genotypes Across California

Epidemic Spread of Symbiotic and Non-Symbiotic Bradyrhizobium Genotypes Across California

Functional characterization of the Bradyrhizobium japonicum modA and modB genes involved in molybdenum transport

Population genomics of Sinorhizobium medicae based on low-coverage sequencing of sympatric isolates

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