Nodulation competitiveness and nitrogenase activity of gusA-marked Rhizobium meliloti in alfalfa

概要

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The gusA-marked Rhizobium meliloti YAO 3 M 2 and YAO 3 M 6 mutants were constructed by inserting transposon mTn 5 SSgusA 20 from Escherichia coli S 17-1 lambda-pir into the genome of Rhizobium meliloti YAO 3, a promising acid-tolerant strain with a high nitrogen-fixing ability isolated from Korean soil. Alfalfa (Medicago sativa L.) plants inoculated with the gusA-marked mutant showed a comparable nodule number and nitrogenase activity to those of the plants inoculated with the wild strain, while nodule occupancy by each mutant did not differ from that of the wild strain. These findings suggest that transposon mutagenesis did not alter the characteristics of the parent strain and both gusA-marked mutant strains could be used in the characterization of the nodulation and competitiveness of R. meliloti YAO 3. The colonization of the root surface and inside of the nodule by the gusA-marked mutants was easily determined due to the production of a blue precipitate after incubation of the nodulated roots in the GUS substrate X-gluc, while the unmarked strain was recognized by the presence of unstained bacteroids in the nodules.
日本土壌微生物学会の論文
1997-10-01