Abstract
A conjugal plasmid which encodes both peak nodulation genes and nitrogenase genes, and which is labeled with the transposon Tn5, was transferred to a wild-type Rhizobium trifolii strain to examine the stability and expression of the host range and fixation (Fix+) phenotypes. Transconjugates were isolated which were shown to initially form nitrogen-fixing nodules (Nod+ Fix+) on both clovers and peas. These hybrid strains were then repeatedly passaged through either pea or clover nodules or onto a solid agar medium to determine whether these broadened-host-range characteristics were stably maintained. An instability was noted in the capacity of some of these hybrids to form nitrogen-fixing nodules on all of the host plants used. The broadened nodulation ability was, however, more readily maintained. In some cases, the changes in the Nod+ Fix+ phenotype could be attributed to demonstrable changes in the plasmid profile of the hybrid strains, whereas in other cases no demonstrable plasmid alterations could be detected.
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- Beringer J. E. R factor transfer in Rhizobium leguminosarum. J Gen Microbiol. 1974 Sep;84(1):188–198. doi: 10.1099/00221287-84-1-188. [DOI] [PubMed] [Google Scholar]
- Eckhardt T. A rapid method for the identification of plasmid desoxyribonucleic acid in bacteria. Plasmid. 1978 Sep;1(4):584–588. doi: 10.1016/0147-619x(78)90016-1. [DOI] [PubMed] [Google Scholar]
- Herridge D. F., Roughley R. J. Variation in colony characteristics and symbiotic effectiveness of Rhizobium. J Appl Bacteriol. 1975 Feb;38(1):19–27. doi: 10.1111/j.1365-2672.1975.tb00495.x. [DOI] [PubMed] [Google Scholar]
- Labandera C. A., Vincent J. M. Loss of symbiotic capacity in commercially useful strains of Rhizobium trifolii. J Appl Bacteriol. 1975 Oct;39(2):209–211. doi: 10.1111/j.1365-2672.1975.tb00563.x. [DOI] [PubMed] [Google Scholar]
- Nutman P. S. Variation within Strains of Clover Nodule Bacteria in Size of Nodule Produced and in "Effectivity" of Symbiosis. J Bacteriol. 1946 Apr;51(4):411–432. [PMC free article] [PubMed] [Google Scholar]
- Prakash R. K., Schilperoort R. A., Nuti M. P. Large plasmids of fast-growing rhizobia: homology studies and location of structural nitrogen fixation (nif) genes. J Bacteriol. 1981 Mar;145(3):1129–1136. doi: 10.1128/jb.145.3.1129-1136.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]