Skip to main content

Genome sequence of the Lotus spp. microsymbiont Mesorhizobium loti strain R7A

Abstract

Mesorhizobium loti strain R7A was isolated in 1993 in Lammermoor, Otago, New Zealand from a Lotus corniculatus root nodule and is a reisolate of the inoculant strain ICMP3153 (NZP2238) used at the site. R7A is an aerobic, Gram-negative, non-spore-forming rod. The symbiotic genes in the strain are carried on a 502-kb integrative and conjugative element known as the symbiosis island or ICEMl SymR7A. M. loti is the microsymbiont of the model legume Lotus japonicus and strain R7A has been used extensively in studies of the plant-microbe interaction. This report reveals that the genome of M. loti strain R7A does not harbor any plasmids and contains a single scaffold of size 6,529,530 bp which encodes 6,323 protein-coding genes and 75 RNA-only encoding genes. This rhizobial genome is one of 100 sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

Introduction

Mesorhizobium loti strain R7A is a reisolate of strain ICMP3513 (International Culture Collection of Microorganisms from Plants, LandCare Research, Auckland, New Zealand). It was isolated from a root nodule taken from a stand of Lotus corniculatus in Lammermoor, Central Otago, New Zealand, inoculated seven years earlier with strain ICMP3153 [1]. Strain ICMP3153 was a recommended inoculant strain for L. corniculatus in New Zealand and is also known as NZP2238 and Lc265Da. In its guise as NZP2238, it was one of the strains used to define the species Rhizobium loti (now Mesorhizobium loti) [2].

Strain R7A contains a 502-kb symbiosis island, also known as ICEMl SymR7A, that was discovered through its ability to transfer from strain ICMP3153 to indigenous nonsymbiotic mesorhizobia at the Lammermoor field site [1, 3]. The symbiosis island encodes 414 genes including all of the genes required for Nod factor synthesis, nitrogen fixation and transfer of the island [4]. Transfer of the island occurs via conjugation involving a rolling-circle process. The transferred island integrates into the chromosome of the recipient cell at the sole phenylalanine tRNA gene. Integration of the island is dependent on a P4-type integrase encoded by intS, located 198 bp downstream of the phe-tRNA gene, which acts on an attachment site (attS) on the circular form of the island and a chromosomal attachment site (attB). Integration of the island reconstructs the entire phe-tRNA gene at one end (arbitrarily termed the left end) and forms a 17-bp repeat of the three-prime end of the phe-tRNA gene at the right end of the integrated island [35].

M. loti is the microsymbiont of the model legume Lotus japonicus and strain R7A together with the first M. loti strain sequenced, strain MAFF303099 [6], have been used extensively with L. japonicus in studies of the plant-microbe interaction. Studies using R7A have included characterization of the symbiotic role of the vir Type IV secretion system encoded by the strain [7], determination of the requirements for Nod factor decorations [8] and exopolysaccharides [9] for efficient nodulation of various Lotus species, and characterization of genes required for symbiotic nitrogen fixation [10]. The regulation of symbiosis island transfer in strain R7A has also been extensively characterized [11]. Here we present a summary classification and a set of general features for M. loti strain R7A together with the description of the complete genome sequence and annotation.

Classification and general features

Mesorhizobium loti strain R7A is in the order Rhizobiales of the class Alphaproteobacteria. Cells are described as non-sporulating, Gram-negative, non-encapsulated, rods. The rod-shaped form varies in size with dimensions of 0.25-0.5 μm in width and 1–1.5 μm in length (Figure 1 Left and 1 Center). They are moderately fast growing, forming 2 mm diameter colonies within 4 days and have a mean generation time of approximately 6 h when grown in TY broth at 28°C [1]. Colonies on G/RDM agar [12] and half strength Lupin Agar (½LA) [13] are opaque, slightly domed, mucoid with smooth margins (Figure 1 Right).

Figure 1
figure1

Images of Mesorhizobium loti strain R7A using scanning (Left) and transmission (Center) electron microscopy and the appearance of colony morphology on ½LA (Right).

Strains of this organism are able to tolerate a pH range between 4 and 10. Carbon source utilization and fatty acid profiles of M. loti have been described previously [2, 14, 15]. Minimum Information about the Genome Sequence (MIGS) is provided in Table 1.

Table 1 Classification and general features of Mesorhizobium loti strain R7A according to the MIGS recommendations [16, 17]

Figure 2 Phylogenetic tree showing the relationships of Mesorhizobium loti R7A with other root nodule bacteria based on aligned sequences of the 16S rRNA gene (1,290 bp internal region). All sites were informative and there were no gap-containing sites. Phylogenetic analyses were performed using MEGA [26], version 5. The tree was built using the Maximum-Likelihood method with the General Time Reversible model [27]. Bootstrap analysis [28] with 500 replicates was performed to assess the support of the clusters. Type strains are indicated with a superscript T. Brackets after the strain name contain a DNA database accession number and/or a GOLD ID (beginning with the prefix G) for a sequencing project registered in GOLD [29]. Published genomes are indicated with an asterisk.

Figure 2
figure2

Shows the phylogenetic neighborhood of M. loti strain R7A in a 16S rRNA gene sequence based tree. This strain has 100% (1,367/1,367 bp) 16S rRNA gene sequence identity to MAFF303099 (GOLD ID: Gc00040) and 99.8% sequence identity (1,364/1,397 bp) to M. opportunistum WSM2075 (GOLD ID: Gc01853).

Symbiotaxonomy

M. loti strain R7A is a field reisolate of strain ICMP3153 that was originally isolated from a Lotus corniculatus nodule in Ireland. It forms effective symbioses with L. tenuis, L. corniculatus, L. japonicus (including ecotypes Gifu and MG-20), L. filicaulis and L. burttii. It also induces but does not infect nodule primordia on L. pedunculatus and Leucaena leucocephala [7, 8]. Mutants of strain R7A defective in the vir Type IV secretion system encoded on the symbiosis island are able to form effective nodules on Leucaena leucocephala but not L. pedunculatus [7]. A nonsymbiotic derivative of R7A cured of the symbiosis island and therefore unable to form root nodules has also been isolated and is called R7ANS [5].

Genome sequencing and annotation information

Genome project history

This organism was selected for sequencing on the basis of its environmental and agricultural relevance to issues in global carbon cycling, alternative energy production, and biogeochemical importance, and is part of the Community Sequencing Program at the U.S. Department of Energy, Joint Genome Institute (JGI) for projects of relevance to agency missions. The genome project is deposited in the Genomes OnLine Database [29] and an improved-high-quality-draft genome sequence in IMG. Sequencing, finishing and annotation were performed by the JGI. A summary of the project information is shown in Table 2.

Table 2 Genome sequencing project information for Mesorhizobium loti R7A

Growth conditions and DNA isolation

M. loti strain R7A was grown to mid logarithmic phase in TY rich medium [30] on a gyratory shaker at 28°C at 250 rpm. DNA was isolated from 60 mL of cells using a CTAB (Cetyl trimethyl ammonium bromide) bacterial genomic DNA isolation method [31].

Genome sequencing and assembly

The draft genome of M. loti R7A was generated at the DOE Joint Genome Institute (JGI) using Illumina data [32]. For this genome, we constructed and sequenced an Illumina short-insert paired-end library with an average insert size of 270 bp which generated 21,315,208 reads and an Illumina long-insert paired-end library with an average insert size of 10487.44 +/- 2154.53 bp which generated 3,077,470 reads totaling 3,659 Mbp of Illumina data (unpublished, Feng Chen). All general aspects of library construction and sequencing performed at the JGI can be found at the DOE Joint Genome Institute website [33].

The initial draft assembly contained 12 contigs in 1 scaffold. The initial draft data was assembled with Allpaths, version 38445, and the consensus was computationally shredded into 10 Kbp overlapping fake reads (shreds). The Illumina draft data were also assembled with Velvet, version 1.1.05 [34], and the consensus sequences were computationally shredded into 1.5 Kbp overlapping fake reads (shreds). The Illumina draft data was assembled again with Velvet using the shreds from the first Velvet assembly to guide the next assembly. The consensus from the second VELVET assembly was shredded into 1.5 Kbp overlapping fake reads. The fake reads from the Allpaths assembly and both Velvet assemblies and a subset of the Illumina CLIP paired-end reads were assembled using parallel phrap, version SPS 4.24 (High Performance Software, LLC). Possible mis-assemblies were corrected with manual editing in Consed [3537]. Gap closure was accomplished using repeat resolution software (Wei Gu, unpublished), and sequencing of bridging PCR fragments with Sanger technology. A total of 40 additional sequencing reactions were completed to close gaps and to raise the quality of the final sequence. There are 3 contigs and 1 scaffold in the current assembly. The estimated size of the genome is 6.5 Mbp and the final assembly is based on 3,659 Mb of Illumina draft data, which provides an average 563× coverage of the genome.

Genome annotation

Genes were identified using Prodigal [38] as part of the Oak Ridge National Laboratory genome annotation pipeline, followed by a round of manual curation using the JGI GenePrimp pipeline [39]. The predicted CDSs were translated and used to search the National Center for Biotechnology Information (NCBI) nonredundant database, UniProt, TIGRFam, Pfam, PRIAM, KEGG, COG, and InterPro databases. These data sources were combined to assert a product description for each predicted protein. Non-coding genes and miscellaneous features were predicted using tRNAscan-SE [40], RNAMMer [41], Rfam [42], TMHMM [43], and SignalP [44]. Additional gene prediction analyses and functional annotation were performed within the Integrated Microbial Genomes (IMG-ER) platform [45].

Genome properties

The genome is 6,529,530 nucleotides with 62.93% GC content (Table 3 and Figure 3) and is comprised of a single scaffold and no plasmids. From a total of 6,398 genes, 6,323 were protein encoding and 75 RNA-only encoding genes. Within the genome, 203 pseudogenes were also identified. The majority of genes (80.10%) were assigned a putative function whilst the remaining genes were annotated as hypothetical. The distribution of genes into COGs functional categories is presented in Table 4.

Table 3 Genome statistics for Mesorhizobium loti R7A
Figure 3
figure3

Graphical map of the single scaffold of Mesorhizobium loti R7A. From bottem to the top: Genes on forward strand (color by COG categories as denoted by the IMG platform), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, sRNAs red, other RNAs black), GC content, GC skew.

Table 4 Number of protein coding genes of Mesorhizobium loti R7A associated with the general COG functional categories

Conclusions

The M. loti R7A genome consists of a single 6.5-Mb chromosome which encodes 6,398 genes. The sequencing was completed to the stage where a single scaffold comprising 3 contigs was obtained. M. loti strain R7A and M. loti strain MAFF303099 are currently the two most widely studied M. loti strains. Strain R7A differs from MAFF303099 in that the genome lacks plasmids whereas the genome of MAFF303099 includes two plasmids pMLa and pMLb [6]. The R7A symbiosis island remains mobile whereas the MAFF303099 symbiosis island is likely immobile due at least in part to a transposon insertion within the origin of transfer (oriT) [3, 5]. M. loti strain R7A represents an important resource for the study of the mechanism and regulation of transfer of large mobile integrative and conjugative elements (ICEs). It is also widely used in conjunction with the model legume Lotus japonicus for ongoing molecular analyses of the plant-microbe interactions required for the establishment of a nitrogen-fixing symbiosis.

References

  1. 1.

    Sullivan JT, Patrick HN, Lowther WL, Scott DB, Ronson CW: Nodulating strains of Rhizobium loti arise through chromosomal symbiotic gene transfer in the environment. Proc Natl Acad Sci U S A 1995, 92: 8985–9. PubMed http://dx.doi.org/10.1073/pnas.92.19.8985 10.1073/pnas.92.19.8985

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  2. 2.

    Jarvis BDW, Pankhurst CE, Patel JJ: Rhizobium loti , a new species of legume root nodule bacteria. Int J Syst Bacteriol 1982, 32: 378–80. http://dx.doi.org/10.1099/00207713–32–3-378 10.1099/00207713-32-3-378

    Article  Google Scholar 

  3. 3.

    Sullivan JT, Ronson CW: Evolution of rhizobia by acquisition of a 500-kb symbiosis island that integrates into a phe-tRNA gene. Proc Natl Acad Sci U S A 1998, 95: 5145–9. PubMed http://dx.doi.org/10.1073/pnas.95.9.5145 10.1073/pnas.95.9.5145

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  4. 4.

    Sullivan JT, Trzebiatowski JR, Cruickshank RW, Gouzy J, Brown SD, Elliot RM, Fleetwood DJ, McCallum NG, Rossbach U, Stuart GS, Weaver JE, Webby RJ, de Bruijn FJ, Ronson CW: Comparative sequence analysis of the symbiosis island of Mesorhizobium loti strain R7A. J Bacteriol 2002, 184: 3086–95. PubMed http://dx.doi.org/10.1128/JB.184.11.3086–3095.2002 10.1128/JB.184.11.3086-3095.2002

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  5. 5.

    Ramsay JP, Sullivan JT, Stuart GS, Lamont IL, Ronson CW: Excision and transfer of the Mesorhizobium loti R7A symbiosis island requires an integrase IntS, a novel recombination directionality factor RdfS, and a putative relaxase RlxS. Mol Microbiol 2006, 62: 723–34. PubMed http://dx.doi.org/10.1111/j.1365–2958.2006.05396.x 10.1111/j.1365-2958.2006.05396.x

    CAS  Article  PubMed  Google Scholar 

  6. 6.

    Kaneko T, Nakamura Y, Sato S, Asamizu E, Kato T, Sasamoto S, Watanabe A, Idesawa K, Ishikawa A, Kawashima K, Kimura T, Kishida Y, Kiyokawa C, Kohara M, Matsumoto M, Matsuno A, Mochizuki Y, Nakayama S, Nakazaki N, Shimpo S, Sugimoto M, Takeuchi C, Yamada M, Tabata S: Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti . DNA Res 2000, 7: 331–8. PubMed http://dx.doi.org/10.1093/dnares/7.6.331 10.1093/dnares/7.6.331

    CAS  Article  PubMed  Google Scholar 

  7. 7.

    Hubber A, Vergunst AC, Sullivan JT, Hooykaas PJJ, Ronson CW: Symbiotic phenotypes and translocated effector proteins of the Mesorhizobium loti strain R7A VirB/D4 type IV secretion system. Mol Microbiol 2004, 54: 561–74. 10.1111/j.1365-2958.2004.04292.x

    CAS  Article  PubMed  Google Scholar 

  8. 8.

    Rodpothong P, Sullivan JT, Songsrirote K, Sumpton D, Cheung KWJT, Thomas-Oates J, Radutoiu S, Stougaard J, Ronson CW: Nodulation gene mutants of Mesorhizobium loti R7A - nodZ and nolL mutants have host-specific phenotypes on Lotus spp. Mol Plant Microbe Interact 2009, 22: 1546–54. PubMed http://dx.doi.org/10.1094/MPMI-22–12–1546 10.1094/MPMI-22-12-1546

    CAS  Article  PubMed  Google Scholar 

  9. 9.

    Kelly SJ, Muszynski A, Kawaharada Y, Hubber AM, Sullivan JT, Sandal N, Carlson RW, Stougaard J, Ronson CW: Conditional requirement for exopolysaccharide in the Mesorhizobium-Lotus symbiosis. Mol Plant Microbe Interact 2013, 26: 319–29. PubMed http://dx.doi.org/10.1094/MPMI-09–12–0227-R 10.1094/MPMI-09-12-0227-R

    CAS  Article  PubMed  Google Scholar 

  10. 10.

    Sullivan JT, Brown SD, Ronson CW: The NifA-RpoN regulon of Mesorhizobium loti strain R7A and its symbiotic activation by a novel LacI/GalR-family regulator. PLoS One 2013,8(1):e53762. PubMed 10.1371/journal.pone.0053762

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  11. 11.

    Ramsay JP, Major AS, Komarovsky VM, Sullivan JT, Dy RL, Hynes MF, Salmond GPC, Ronson CW: A widely conserved molecular switch controls quorum sensing and symbiosis island transfer in Mesorhizobium loti through expression of a novel antiactivator. Mol Microbiol 2013, 87: 1–13. PubMed http://dx.doi.org/10.1111/mmi.12079 10.1111/mmi.12079

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    Ronson CW, Nixon BT, Albright LM, Ausubel FM: Rhizobium meliloti ntrA ( rpoN ) gene is required for diverse metabolic functions. J Bacteriol 1987, 169: 2424–31. PubMed

    PubMed Central  CAS  PubMed  Google Scholar 

  13. 13.

    Howieson JG, Ewing MA, D'antuono MF: Selection for acid tolerance in Rhizobium meliloti . Plant Soil 1988, 105: 179–88. http://dx.doi.org/10.1007/BF02376781 10.1007/BF02376781

    CAS  Article  Google Scholar 

  14. 14.

    Jarvis BDW, Van Berkum P, Chen WX, Nour SM, Fernandez MP, Cleyet-Marel JC, Gillis M: Transfer of Rhizobium loti, Rhizobium huakuii, Rhizobium ciceri, Rhizobium mediterraneum, Rhizobium tianshanense to Mesorhizobium gen.nov. Int J Syst Evol Microbiol 1997, 47: 895–8.

    Google Scholar 

  15. 15.

    Tighe SW, de Lajudie P, Dipietro K, Lindstrom K, Nick G, Jarvis BDW: Analysis of cellular fatty acids and phenotypic relationships of Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium species using the Sherlock Microbial Identification System. Int J Syst Evol Microbiol 2000, 50: 787–801. PubMed http://dx.doi.org/10.1099/00207713–50–2-787 10.1099/00207713-50-2-787

    CAS  Article  PubMed  Google Scholar 

  16. 16.

    Field D, Garrity G, Gray T, Morrison N, Selengut J, Sterk P, Tatusova T, Thomson N, Allen M, Angiuoli SV, Ashburner M, Axelrod N, Baldauf S, Ballard S, Boore JL, Cochrane G, Cole J, Dawyndt P, de Vos P, de Pamphilis C, Edwards R, Faruque N, Feldman R, Gilbert J, Gilna P, Glöckner FO, Goldstein P, Guralnick R, Haft D, Hancock D, et al.: Towards a richer description of our complete collection of genomes and metagenomes “Minimum Information about a Genome Sequence” (MIGS) specification. Nat Biotechnol 2008, 26: 541–7. PubMed http://dx.doi.org/10.1038/nbt1360 10.1038/nbt1360

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  17. 17.

    Woese CR, Kandler O, Wheelis ML: Towards a natural system of organisms: proposal for the domains Archaea , Bacteria, and Eucarya. Proc Natl Acad Sci U S A 1990, 87: 4576–9. PubMed http://dx.doi.org/10.1073/pnas.87.12.4576 10.1073/pnas.87.12.4576

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  18. 18.

    Garrity GM, Bell JA, Lilburn T, Phylum XIV: Proteobacteria phyl. nov. In Bergey's Manual of Systematic Bacteriology. Second Edition, Volume 2, Part B edition. Edited by: Garrity GM, Brenner DJ, Krieg NR, Staley JT. New York: Springer; 2005:1.

    Chapter  Google Scholar 

  19. 19.

    Garrity GM, Bell JA, Lilburn T: Class I. Alphaproteobacteria class. In Bergey's Manual of Systematic Bacteriology. Second edition. Edited by: Garrity GM, Brenner DJ, Kreig NR, Staley JT. New York: Springer - Verlag; 2005.

    Google Scholar 

  20. 20.

    Kuykendall LD: Order VI. Rhizobiales ord. nov. In Bergey's Manual of Systematic Bacteriology. Second edition. Edited by: Garrity GM, Brenner DJ, Kreig NR, Staley JT. New York: Springer - Verlag; 2005:324.

    Google Scholar 

  21. 21.

    Validation List No. 107. List of new names and new combinations previously effectively, but not validly, published Int J Syst Evol Microbiol 2006, 56: 1–6. PubMed http://dx.doi.org/10.1099/ijs.0.64188–0

  22. 22.

    Mergaert J, Swings J, Family IV: Phyllobacteriaceae . In Bergy's Manual of Systematic Bacteriology. Second edition. Edited by: Garrity GM, Brenner DJ, Kreig NR, Staley JT. New York: Springer - Verlag; 2005:393.

    Google Scholar 

  23. 23.

    Jarvis BDW, Van Berkum P, Chen XW, Nour SM, Fernandez MP, Cleyet-Marel JC, Gillis M: Transfer of Rhizobium loti, Rhizobium huakuii, Rhizobium ciceri, Rhizobium mediterraneum and Rhizobium tianshanense to Mesorhizobium gen. nov. Int J Syst Bacteriol 1997, 47: 895–8. http://dx.doi.org/10.1099/00207713–47–3-895 10.1099/00207713-47-3-895

    Article  Google Scholar 

  24. 24.

    Biological Agents: Technical rules for biological agents. TRBA.466. http://www.baua.de

  25. 25.

    Ashburner M, Ball CA, Blake JA, Botstein D, Butler H, Cherry JM, Davis AP, Dolinski K, Dwight SS, Eppig JT, Harris MA, Hill DP, Issel-Tarver L, Kasarskis A, Lewis S, Matese JC, Richardson JE, Ringwald M, Rubin GM, Sherlock G: Gene ontology: tool for the unification of biology. The Gene Ontology Consortium. Nat Genet 2000, 25: 25–9. PubMed http://dx.doi.org/10.1038/75556 10.1038/75556

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  26. 26.

    Tamura K, Peterson D, Peterson N, Stecher G, Nei M, Kumar S: MEGA5: Molecular Evolutionary Genetics Analysis using Maximum Likelihood, Evolutionary Distance, and Maximum Parsimony Methods. Mol Biol Evol 2011, 28: 2731–9. PubMed http://dx.doi.org/10.1093/molbev/msr121 10.1093/molbev/msr121

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  27. 27.

    Nei M, Kumar S: Molecular Evolution and Phylogenetics. New York: Oxford University Press; 2000.

    Google Scholar 

  28. 28.

    Felsenstein J: Confidence limits on phylogenies: an approach using the bootstrap. Evolution 1985, 39: 783–91. http://dx.doi.org/10.2307/2408678 10.2307/2408678

    Article  Google Scholar 

  29. 29.

    Liolios K, Mavromatis K, Tavernarakis N, Kyrpides NC: The Genomes On Line Database (GOLD) in 2007: status of genomic and metagenomic projects and their associated metadata. Nucleic Acids Res 2008, 36: D475–9. PubMed http://dx.doi.org/10.1093/nar/gkm884 10.1093/nar/gkn240

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  30. 30.

    Beringer JE: R factor transfer in Rhizobium leguminosarum . J Gen Microbiol 1974, 84: 188–98. PubMed http://dx.doi.org/10.1099/00221287–84–1-188 10.1099/00221287-84-1-188

    CAS  Article  PubMed  Google Scholar 

  31. 31.

    DOE Joint Genome Institute user homepage. http://my.jgi.doe.gov/general/index.html

  32. 32.

    Bennett S, Solexa L: Pharmacogenomics. 2004, 5: 433–8. PubMed http://dx.doi.org/10.1517/14622416.5.4.433 10.1517/14622416.5.4.433

    Article  PubMed  Google Scholar 

  33. 33.

    DOE Joint Genome Institute. http://www.jgi.doe.gov/

  34. 34.

    Zerbino DR: Using the Velvet de novo assembler for short-read sequencing technologies. Curr Protoc Bioinformatics 2010, Chapter 11: 11–5.

    Google Scholar 

  35. 35.

    Ewing B, Green P: Base-calling of automated sequencer traces using phred. II. Error probabilities. Genome Res 1998, 8: 186–94. PubMed http://dx.doi.org/10.1101/gr.8.3.175

    CAS  Article  PubMed  Google Scholar 

  36. 36.

    Ewing B, Hillier L, Wendl MC, Green P: Base-calling of automated sequencer traces using phred. I. Accuracy assessment. Genome Res 1998, 8: 175–85. PubMed http://dx.doi.org/10.1101/gr.8.3.175 10.1101/gr.8.3.175

    CAS  Article  PubMed  Google Scholar 

  37. 37.

    Gordon D, Abajian C, Green P: Consed: a graphical tool for sequence finishing. Genome Res 1998, 8: 195–202. PubMed http://dx.doi.org/10.1101/gr.8.3.195 10.1101/gr.8.3.195

    CAS  Article  PubMed  Google Scholar 

  38. 38.

    Hyatt D, Chen GL, Locascio PF, Land ML, Larimer FW, Hauser LJ: Prodigal: prokaryotic gene recognition and translation initiation site identification. Bioinformatics 2010, 11: 119. PubMed http://dx.doi.org/10.1186/1471–2105–11–119

    PubMed Central  PubMed  Google Scholar 

  39. 39.

    Pati A, Ivanova NN, Mikhailova N, Ovchinnikova G, Hooper SD, Lykidis A, Kyrpides NC: GenePRIMP: a gene prediction improvement pipeline for prokaryotic genomes. Nat Methods 2010, 7: 455–7. PubMed http://dx.doi.org/10.1038/nmeth.1457 10.1038/nmeth.1457

    CAS  Article  PubMed  Google Scholar 

  40. 40.

    Lowe TM, Eddy SR: tRNAscan-SE: a program for improved detection of transfer RNA genes in genomic sequence. Nucleic Acids Res 1997, 25: 955–964. PubMed http://dx.doi.org/10.1093/nar/25.5.0955 10.1093/nar/25.5.0955

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  41. 41.

    Lagesen K, Hallin P, Rodland EA, Staerfeldt HH, Rognes T, Ussery DW: RNAmmer: consistent and rapid annotation of ribosomal RNA genes. Nucleic Acids Res 2007, 35: 3100–8. PubMed http://dx.doi.org/10.1093/nar/gkm160 10.1093/nar/gkm160

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  42. 42.

    Griffiths-Jones S, Bateman A, Marshall M, Khanna A, Eddy SR: Rfam: an RNA family database. Nucleic Acids Res 2003, 31: 439–41. PubMed http://dx.doi.org/10.1093/nar/gkg006 10.1093/nar/gkg006

    PubMed Central  CAS  Article  PubMed  Google Scholar 

  43. 43.

    Krogh A, Larsson B, von Heijne G, Sonnhammer EL: Predicting transmembrane protein topology with a hidden Markov model: application to complete genomes. J Mol Biol 2001, 305: 567–80. PubMed http://dx.doi.org/10.1006/jmbi.2000.4315 10.1006/jmbi.2000.4315

    CAS  Article  PubMed  Google Scholar 

  44. 44.

    Bendtsen JD, Nielsen H, von Heijne G, Brunak S: Improved prediction of signal peptides: SignalP 3.0. J Mol Biol 2004, 340: 783–95. PubMed http://dx.doi.org/10.1016/j.jmb.2004.05.028 10.1016/j.jmb.2004.05.028

    Article  PubMed  Google Scholar 

  45. 45.

    Markowitz VM, Mavromatis K, Ivanova NN, Chen IM, Chu K, Kyrpides NC: IMG ER: a system for microbial genome annotation expert review and curation. Bioinformatics 2009, 25: 2271–8. PubMed http://dx.doi.org/10.1093/bioinformatics/btp393 10.1093/bioinformatics/btp393

    CAS  Article  PubMed  Google Scholar 

Download references

Acknowledgements

This work was performed under the auspices of the US Department of Energy Office of Science, Biological and Environmental Research Program, and by the University of California, Lawrence Berkeley National Laboratory under contract No. DE-AC02-05CH11231, Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344, and Los Alamos National Laboratory under contract No. DE-AC02-06NA25396.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Wayne Reeve.

Additional information

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

JS and CR supplied the strain and background information for this project and helped WR write the paper, TR supplied DNA to JGI and performed all imaging, WR coordinated the project and all other authors were involved in either sequencing the genome and/or editing the paper. All authors read and approved the final manuscript.

Authors’ original submitted files for images

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

The Creative Commons Public Domain Dedication waiver (https://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kelly, S., Sullivan, J., Ronson, C. et al. Genome sequence of the Lotus spp. microsymbiont Mesorhizobium loti strain R7A. Stand in Genomic Sci 9, 6 (2014). https://doi.org/10.1186/1944-3277-9-6

Download citation

Keywords

  • Root-nodule bacteria
  • Nitrogen fixation
  • Symbiosis
  • Alphaproteobacteria