Abstract
Allan Downie, in his commendable News and Views discussion1 of our work2, suggests that a second, non-chromosomal symbiotic replicon could be present in the bacterial Rhizobium species NGR234. So far, our as-yet unpublished work on physical mapping and random sequencing of the NGR234 genome by V. Viprey, C. Freiberg and X. P. has produced no evidence of another plasmid. Further, the electrophoretic methods we used could visualize the twin symbiotic plasmids (relative molecular mass (Mr) 1×109) of R. meliloti, but in the event consistently demonstrated only a single plasmid of Mr3.1×108± 2×107 in NGR234 (refs 3, 4). Thus, although Morrison et al.5 reported that NGR234 contains two plasmids of Mr3×108 and 4.5×108, it seems unlikely that a second plasmid exists. It is true, however, that some nodulation and other symbiotic genes map to the chromosome6. (Incidentally, the fixABC cluster is present on pNGR234a.)
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
References
Downie, A. Nature 387, 352–354 (1997).
Freiberg, C. et al. Nature 387, 394–401 (1997).
Broughton, W. J., Heycke, N., Meyer z. A., H. & Pankhurst, C. E. Proc. Natl Acad. Sci. USA 81, 3093–3097 (1984).
Broughton, W. J. et al. Arch. Microbiol. 141, 14–21 (1985).
Morrison, N. A. et al. J. Bacteriol. 160, 483–487 (1984).
Perret, X., Broughton, W. J. & Brenner, S. Proc. Natl Acad. Sci. USA 88, 1923–1927 (1991).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Perret, X., Broughton, W. How many replicons make a nodule?. Nature 387, 767 (1997). https://doi.org/10.1038/42840
Issue Date:
DOI: https://doi.org/10.1038/42840
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.