Characterization of pigmented methylotrophic bacteria which nodulate Lotononis bainesii.

Root nodule isolates from a shrubby legume, Lotononis bainesii, were characterized by 16S rRNA gene sequencing and morphologically by substrate utilization patterns. The symbiotic genome of these isolates was analysed by partial sequencing of the nifH gene. Based on the results of numerical taxonomy, the isolates formed a closely related cluster, showing no correspondence to any of the known rhizobial clusters.

Unaltered Nodulation Competitiveness of a Strain of Bradyrhizobium sp. (Lotus) after a Decade in Soil.

A Bradyrhizobium sp. (Lotus) strain that formed a soil population that was highly competitive for nodulation of Lotus pedunculatus 11 years after its introduction into a field soil and a culture of the same strain stored lyophilized were compared with an antibiotic-resistant mutant in respect of their nodulation competitiveness. The mutant was less competitive than the wild-type strain it was isolated from and had to be present at a cell ratio of 5.

Differences in properties of peanut seed lectin and purified galactose- and mannose-binding lectins from nodules of peanut.

Two lectins were purified by affinity chromatography from mature peanut (Arachis hypogaea L.) nodules, and compared with the previously characterised seed lectin of this plant. One of the nodule lectins was similar to the seed lectin in its molecular weight and amino-acid composition and ability to bind derivatives of galactose.

Detection of lectins in nodulated peanut and soybean plants.

The direct double-antibody enzymelinked immunosorbent assay system was used in the detection and measurement of seed lectins from peanut (Arachis hypogaea L.) and soybean (Glycine max L.) plants (PSL and SBL, respectively) that had been inoculated with their respective rhizobia.

Susceptibility of Agrobacterium tumefaciens Strains to Two Agrocin-Producing Agrobacterium Strains.

Sixty-five strains and isolates of Agrobacterium tumefaciens representing each of the known biotypes, were tested for in vitro and in vivo susceptibility to the agrocin-producing strains Agrobacterium radiobacter 84 and A. tumefaciens D286. No biotype 3 strain was susceptible to the effects of either of the agrocinogenic strains in vitro.

Effectiveness of Rhizobium strains used in inoculants after their introduction into soil.

Rhizobium strains used in inoculants for Trifolium spp., Medicago spp., Glycine max, and Lotus pedunculatus were isolated from nodules of these legumes grown in soils into which the rhizobia had been introduced 4 to 8 years before.

Role of Lectins in the Specific Recognition of Rhizobium by Lotononis bainesii.

Fluorescein isothiocyanate (FITC)-labeled lectin purified from the root of Lotononis bainesii Baker was bound by cells of five out of seven L. bainesii-nodulating strains of Rhizobium under culture conditions. With the exception of a strain of Rhizobium leguminosarum, strains of noninfective rhizobia failed to bind the root lectin under these conditions.

Properties of Lectins in the Root and Seed of Lotononis bainesii.

A lectin was purified from the root of Lotononis bainesii Baker by affinity chromatography on Sepharose-blood group substance A + H. The molecular weight of the lectin was estimated by gel filtration to be 118,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the lectin was a tetramer composed of two slightly different subunits with respective molecular weights of 32,000 and 35,000.

Competitive Abilities of Rhizobium meliloti Strains Considered to Have Potential as Inoculants.

Twenty four strains of Rhizobium meliloti considered to have potential for inoculant production were grouped in pairs and tested for their ability to compete for nodulation on Medicago sativa, Medicago truncatula, and Medicago littoralis. At the outset, each pair of strains, which consisted of a wild type and a selected streptomycin-resistant mutant of another strain, was tested in an autoclaved soil. Six strain pairs, each consisting of a good and a poor competitor, reacted consistently when tested in each of five other autoclaved soils; eight pairs consisting of strains with comparable competitive abilities varied in their reactions in some of the soils, or even in the same soil when retested.

Root Surface Association in Relation to Nodulation of Medicago sativa.

Nine strains of Rhizobium meliloti, ranging in competitive ability on Medicago sativa from excellent to poor in autoclaved soils, were paired in 29 combinations and used to inoculate M. sativa in a liquid rooting medium. A positive correlation (r = 0.

Effect of steam sterilization and gamma irradiation of peat on quality of Rhizobium inoculants.

Data obtained by independent tests on each of 483 batches of Rhizobium inoculants for Glycine max, Medicago sativa, and Arachis hypogaea, manufactured commercially in South Africa, are reported and discussed. Whereas the average cell count per gram per batch was well in excess of 10, inoculants for G. max and M.