D. H. Demezas

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Allozyme electrophoresis and restriction fragment length polymorphism (RFLP) analyses were used to examine the genetic diversity of a collection of 18 Rhizobium leguminosarum bv. trifolii, 1 R. leguminosarum bv. viciae, and 2 R. meliloti strains. Allozyme analysis at 28 loci revealed 16 electrophoretic types. The mean genetic distance between(More)
Genetic instability within strains of rhizobia maintained on laboratory media is well recognized, although rarely has the mutation been characterized. Variability within a strain introduced into the field is very difficult to recognise due to poor understanding of naturally-occurring populations of rhizobia. We have examined populations of Rhizobium(More)
We examined the genetic and plasmid diversity within natural populations of Pseudomonas syringae isolated from three ornamental pear nurseries in eastern Oklahoma. The bactericide spray regimen differed at each nursery; copper and streptomycin, only copper, and no bactericides were applied at nurseries I, II, and III respectively. Resistance to copper (Cur)(More)
Indigenous serotype 1-01 of Rhizobium trifolii occupied significantly fewer nodules (6%) on plants of soil-grown noninoculated subterranean clover (Trifolium subterraneum L.) cv. Woogenellup than on cv. Mt. Barker (36%) sampled at the flowering stage of growth. Occupancy by indigenous serotype 2-01, was not significantly different on the two cultivars (16(More)
The symbiotic characteristics of Rhizobium trifolii strains 1-01 and 2-01 were evaluated both individually and in various combinations on two cultivars (Mt. Barker and Woogenellup) of subterranean clover (Trifolium subterraneum L.). Nodules were observed on day 8 independent of cultivar or strain. Cultivar differences were measured in nodulating efficiency(More)
Indigenous serotypes 1-01 and 2-02 of Rhizobium trifolii occupied similar percentages (18 to 23%) of root nodules on soil-grown subclover (Trifolium subterraneum L.) and were virtually absent (4.5%) from nodules of soil-grown white clover (Trifolium repens L.). In contrast (with the exception of one dilution [10]), serotype 1-01 occupied a substantial(More)
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