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Appl. Environ. Microbiol., Apr 1995, 1194-1200, Vol 61, No. 4
CJ Madrzak, B Golinska, J Kroliczak, K Pudelko, D Lazewska, B Lampka and MJ Sadowsky
Genetic structure in field populations of Bradyrhizobium japonicum isolated
in Poland was determined by using several complementary techniques. Of the
10 field sites examined, only 4 contained populations of indigenous B.
japonicum strains. The Polish bradyrhizobia were divided into at least two
major groups on the basis of protein profiles on polyacrylamide gels,
serological reaction with polyclonal antisera, repetitive extragenic
palindromic PCR fingerprints of genomic DNA, and Southern hybridization
analyses with nif and nod gene probes. Serological analyses indicated that
87.5% of the Polish B. japonicum isolates tested were in serogroups 123 and
129, while seven (12.5%) of the isolates tested belonged to their own
unique serogroup. These seven strains also could be grouped together on the
basis of repetitive extragenic palindromic PCR fingerprints, protein
profiles, and Southern hybridization analyses. Cluster analyses indicated
that the seven serologically undefined isolates were genetically dissimilar
from the majority of the Polish B. japonicum strains. Moreover,
immuno-cross-adsorption studies indicated that although the Polish B.
japonicum strains reacted with polyclonal antisera prepared against strain
USDA123, the majority failed to react with serogroup 123- and 129-specific
antisera, suggesting that Polish bradyrhizobia comprise a unique group of
root nodule bacteria which have only a few antigens in common with strains
USDA123 and USDA129. Nodulation studies indicated that members of the
serologically distinct group were very competitive for nodulation of
Glycine max cv. Nawiko. None of the Polish serogroup 123 or 129 isolates
were restricted for nodulation by USDA123- and USDA129-restricting soybean
plant introduction genotypes. Taken together, our results indicate that
while genetically diverse B. japonicum strains were isolated from some
Polish soils, the majority of field sites contained no soybean-nodulating
bacteria. In addition, despite the lack of long-term soybean production in
Poland, field populations of unique B. japonicum strains are present in
some Polish soils and these strains are very competitive for nodulation of
currently used Polish soybean varieties.
Copyright © 1995, American Society for Microbiology
Diversity among Field Populations of Bradyrhizobium japonicum in Poland
Institute of Biochemistry, University of Agriculture, Poznan, Poland, and Departments of Soil Science and Microbiology, University of Minnesota, St. Paul, Minnesota 55108
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