Abstract
Bacteria that form nitrogen-fixing nodules on the roots of plants have been the subject of much research over the past twenty years. This has led to major breakthroughs in understanding how bacteria interact with plants and fix nitrogen. The model system most extensively studied is the interaction between the bacterium Rhizobium meliloti and alfalfa. The R. meliloti genome consists of three replicons, a chromosome of 3540 Kb and two megaplasmids, pSym (pRmeSU47a) and pExo (pRmeSU47b), of 1340 and 1700 Kb respectively (Honeycutt et al., 1993). Each of these plasmids is larger in overall size than the genomes of some bacteria, such as Mycoplasma genitalium (580 Kb) (Fraser et al., 1995). They contain many genes involved in the formation of nitrogen-fixing nodules, as well as genes important for survival and, presumably, competitiveness of the organism within the soil. The nature of these genes is of major current interest.
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References
Charles TC and Finan TM 1990. Analysis of a 1600-Kilobase Rhizobium meliloti Megaplasmid Using Defined Deletions Generated in Vivo. Genetics 127, 5–20.
Charles TC and Finan TM 1991. Genetic Map of Rhizobium meliloti Megaplasmid pRmeSU47b. J. Bac. 172, 2469–2476.
Durland RH and Helinski DR 1990. Replication of the Broad-Host-Range Plasmid RK2: Direct Measurement of Intracellular Concentrations of the Essential TrfA Replication Proteins and Their Effect on Plasmid Copy Number. J. Bac. 172, 3849–3858.
Fleischmann RD, Adams MD, White O, Clayton RA, Kirkness EF, Kerlavage AR, Bult CJ, Tomb JF, Dougherty BA, Merrick JM, et al. 1995. Whole-genome random sequencing and assembly of Haemophilus influenzae Rd. Science 269, 496–512.
Fraser CM, Gocayne JD, White O, Adams MD, Clayton RA, Fleischmann RD, Bult CJ, Kerlavage AR, Sutton G, Kelley JM, et al. 1995. The minimal gene complement of Mycoplasma genitalium. Science 270, 397–403.
Honeycutt RJ, McClelland M, and Sobral BWS 1993. Physical Map of the Genome of Rhizobium meliloti 1021. J. Bac. 175, 6945–6952.
Konieczny I, Doran KS, Helinski DR, and Blasina A 1997. Role of TrfA and DnaA Proteins in Origin Opening during Initiation of DNA Replication of the Broad Host Range Plasmid RK2. J. Biol. Chem. 272,20173–20178.
Pósfai G, Koob M, Hradecná Z, Hasan N, Filutowicz M, and Szybalski W 1994. In vivo excision and ampli-fication of large segments of the Escherichia cou genome. Nucleic Acids Res. 22, 2392–2398.
Sadowski P 1995. The Flp Recombinase of the 2-pm Plasmid of Saccharomyces cerevisiae. Prog. Nucleic Acid Res. Mol. Biol. 51, 53–91.
Wild J, Hradecná Z, Pósfai G, and Szybalski W 1996. A broad-host-range in vivo pop-out and amplification system for generating large quantities of 50- to 100-kb genomic fragments for direct DNA sequencing. Gene 179, 181–188.
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Chain, P.S.G., Hernández-Lucas, I., Golding, B., Finan, T.M. (1999). Cloning Defined Regions of the pExo Megaplasmid of Rhizobium (Sinorhizobium) Meliloti . In: Martĺnez, E., Hernández, G. (eds) Highlights of Nitrogen Fixation Research. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-4795-2_35
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DOI: https://doi.org/10.1007/978-1-4615-4795-2_35
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