In Rhizobium strains the transcription of symbiosis plasmid-localized nod genes, except nodD, is induced by plant flavonoids and requires the nodD gene product. In order to localize NodD protein in R. leguminosarum, a NodD protein-specific antiserum was raised against a lacZ'-'nodD gene fusion product. Using these antibodies, we determined that the NodD protein is located exclusively in the cyt...

Several isolates of Rhizobium fredii were examined for their serological relatedness to each other, to Bradyrhizobium japonicum, and to other fast- and slow-growing rhizobia. Immunofluorescence, agglutination, and immunodiffusion analyses indicated that R. fredii contains at least three separate somatic serogroups, USDA 192, USDA 194, and USDA 205. There was no cross-reaction between any of the...

The response of pea (Pisum sativum cv. Avola) to arbuscular micorrizal fungi (AM) species Glomus mosseae and Glomus intraradices and Rhizobium leguminosarum bv. Viciae, strain D293 regarding growth, nodulation and nitrogen fixing activity was studied. Pea plants (Pisum sativum cv. Avola) were grown in a glasshouse until flowering stage (35 days) in 4 kg plastic pots using leached cinnamonic for...

A new Rhizobium species that nodulates Phaseolus vulgaris L. and Leucaena spp. is proposed on the basis of the results of multilocus enzyme electrophoresis, DNA-DNA hybridization, an analysis of ribosomal DNA organization, a sequence analysis of 16S rDNA, and an analysis of phenotypic characteristics. This taxon, Rhizobium tropici sp. nov., was previously named Rhizobium leguminosarum biovar ph...

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. sativa manufactured with peat treated with gamma irradiation at a dose of 50 kGr co...

The present study was aimed to use spent wash as a substitute for expensive commercial media for Rhizobial cultures. Growth of Rhizobium strains at different concentrations of spent wash was observed and found maximum at 50% spent wash. Bacteria were grown on 50% spent wash which produced remarkable results and competed with standard media like tryptone yeast extract, Rhizobium minimal and yeas...

Cosmids containing hydrogen uptake genes have previously been isolated in this laboratory. Four new cosmids that contain additional hup gene(s) have now been identified by conjugal transfer of a Rhizobium japonicum 122DES gene bank into a Tn5-generated Hup(-) mutant and screening for the acquisition of Hup activity. The newly isolated cosmids, pHU50-pHU53, contain part of the previously isolate...

The Bradyrhizobium japonicun strains SEMIA 5073, SEMIA 5074, SEMIA 5079 and SEMIA 5080 were grown in vitro using Vincent medium combined with different rates of the herbicides imazaquin (0, 0.04, 0.12, 0.24, 0.36 μg a.i. g), clomazone (0, 0.4, 0.8, 1.6 and 3.2 μg a.i. g) and sulfentrazone (0, 0.2, 0.4, 0.8 and 1.6 μg a.i. g) to evaluate the strains tolerance to herbicides. The three herbicides ...

Parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with a Rhizobium species. The bacterial strain RP501 is a slow-growing strain of Rhizobium isolated from Parasponia nodules. Strain RP501 also nodulates the legumes siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata). Using a cosmid clo...

The evolution of mutualisms under novel selective pressures will play a key role in ecosystem responses to environmental change. Because fixed nitrogen is traded in plant–rhizobium mutualisms, increasing N availability in the soil is predicted to alter coevolution of these interactions. Legumes typically decrease the number of associations (nodules) with rhizobia in response to nitrate, but the...