Abstract
In some Rhizobium-legume symbioses, compounds known as rhizopines are synthesized by bacteroids and subsequently catabolized by free-living cells of the producing strain. It has been suggested than rhizopines act as proprietary growth substrates and enhance the competitive ability of the producing strain in its interactions with the diverse microbial community found within the rhizosphere. Wild-type, rhizopine-producing Rhizobium meliloti L5-30 and mutant L5-30 strains deficient for either rhizopine synthesis or catabolism were inoculated onto lucerne host plants in competition experiments. These experiments demonstrated that no apparent advantage resulted from the ability to synthesize a rhizopine, whereas the ability to catabolize rhizopine provided a clear advantage when an organism was in competition with a strain without this ability. The results suggest that when an organism is in competition with a catabolism-deficient mutant, the ability to catabolize rhizopine results in enhanced rates of nodulation. The results of the experiments were not consistent with the hypothesis that the sole role of rhizopines is to act as proprietary growth substrates for the free-living population of the producing strain.
Full Text
The Full Text of this article is available as a PDF (202.3 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Beringer J. E., Brewin N., Johnston A. W., Schulman H. M., Hopwood D. A. The Rhizobium--legume symbiosis. Proc R Soc Lond B Biol Sci. 1979 Apr 11;204(1155):219–233. doi: 10.1098/rspb.1979.0024. [DOI] [PubMed] [Google Scholar]
- Caetano-Anollés G., Gresshoff P. M. Plant genetic control of nodulation. Annu Rev Microbiol. 1991;45:345–382. doi: 10.1146/annurev.mi.45.100191.002021. [DOI] [PubMed] [Google Scholar]
- Murphy P. J., Heycke N., Banfalvi Z., Tate M. E., de Bruijn F., Kondorosi A., Tempé J., Schell J. Genes for the catabolism and synthesis of an opine-like compound in Rhizobium meliloti are closely linked and on the Sym plasmid. Proc Natl Acad Sci U S A. 1987 Jan;84(2):493–497. doi: 10.1073/pnas.84.2.493. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Murphy P. J., Heycke N., Trenz S. P., Ratet P., de Bruijn F. J., Schell J. Synthesis of an opine-like compound, a rhizopine, in alfalfa nodules is symbiotically regulated. Proc Natl Acad Sci U S A. 1988 Dec;85(23):9133–9137. doi: 10.1073/pnas.85.23.9133. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Paau A. S., Bloch C. B., Brill W. J. Developmental fate of Rhizobium meliloti bacteroids in alfalfa nodules. J Bacteriol. 1980 Sep;143(3):1480–1490. doi: 10.1128/jb.143.3.1480-1490.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rao J. P., Grzemski W., Murphy P. J. Rhizobium meliloti lacking mosA synthesizes the rhizopine scyllo-inosamine in place of 3-O-methyl-scyllo-inosamine. Microbiology. 1995 Jul;141(Pt 7):1683–1690. doi: 10.1099/13500872-141-7-1683. [DOI] [PubMed] [Google Scholar]
- Rossbach S., Rasul G., Schneider M., Eardly B., de Bruijn F. J. Structural and functional conservation of the rhizopine catabolism (moc) locus is limited to selected Rhizobium meliloti strains and unrelated to their geographical origin. Mol Plant Microbe Interact. 1995 Jul-Aug;8(4):549–559. doi: 10.1094/mpmi-8-0549. [DOI] [PubMed] [Google Scholar]
- Saint C. P., Wexler M., Murphy P. J., Tempé J., Tate M. E., Murphy P. J. Characterization of genes for synthesis and catabolism of a new rhizopine induced in nodules by Rhizobium meliloti Rm220-3: extension of the rhizopine concept. J Bacteriol. 1993 Aug;175(16):5205–5215. doi: 10.1128/jb.175.16.5205-5215.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Simonsen L. Dynamics of plasmid transfer on surfaces. J Gen Microbiol. 1990 Jun;136(6):1001–1007. doi: 10.1099/00221287-136-6-1001. [DOI] [PubMed] [Google Scholar]