Complementary Methodologies to Delineate the Composition of Rhizobium trifolii Populations in Root Nodules1
- M. H. Dughri and
- P. J. Bottomley2
Three methods of strain identification were used to determine the composition of the Rhizobium trifolii population in nodules formed on subterranean clover (Trifolium subterraneum L. cv. Mt. Barker) inoculated with a soil suspension. Sodium dodecyl sulfate polyacrylamide gradient gel electrophoresis (SDS-PAGGE) was used in a microslab system to elucidate the protein profiles of 22 isolates of R. trifolii. Tube agglutination serological tests carried out with antisera raised to four isolates showed that four groups of isolates could be recognized. Only four isolates out of 22 agglutinated with more than one antiserum, although they reacted with only one antiserum in the gel-immune-diffusion test. One isolate did not react with any of the four antisera. No group of isolates dominated the nodule population. Gel-immune-diffusion analysis showed that isolates from two of the four groups were serologically identical whereas isolates from the other two groups were serologically heterogeneous. Isolates within all four serogroups were subdivided further according to their protein profiles. Many of the isolates within individual groups had very closely similar or identical profiles whereas others were very distinct. Isolates identified as very similar or identical by SDS-PAGGE had the same symbiotic effectiveness on T. subterraneum. The data illustrate the need for multiple methods of identification for the best delineation of the composition of the nodule population.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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