Evidence for a Strain of Rhizobium meliloti Dominating the Nodules of Alfalfa1
- M. B. Jenkins and
- P. J. Bottomley2
Little is known about the composition of indigenous populations of Rhizobium meliloti in agricultural soils. Analysis of 32 isolates of Rhizobium meliloti obtained from root nodules of noninoculated field grown ‘Anchor’ alfalfa (Medicago sativa L.) by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that 12 and six isolates were represented by two protein profiles (A and B), respectively. The remaining 14 isolates were each represented by unique protein profiles. Antiserum raised to isolate 31 (protein profile A) cross-agglutinated with the 12 isolates possessing the same profile and with only two of the remaining 20 isolates represented by different protein profiles. Gel-immune-diffusion analyses showed that nine of the 12 isolates with protein profile A were antigenically identical to isolate 31. Forty-two of 79 nodule isolates, recovered two yr later from the same plot area, were identical to isolate 31 and were found in nodules on plants growing throughout the plot area. The identification of a member of a diverse soil population of R. meliloti, which persists and nodulates extensively over several growing seasons is an important first step in any attempt to clarify the role of soil rhizobia in the problems of inoculant strain competition and persistence.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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