Leguminous plants can enter into root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. An intriguing but still poorly understood property of the symbiosis is its host specificity, which is controlled at multiple levels involving both rhizobial and host genes. It is widely believed that the host specificity is determined by specific recognition of bacterially derived Nod fa...

The products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (LCOs), which are host-specific signal molecules required for nodule formation. The presence of an O-acetyl group on C-6 of the nonreducing N-acetylglucosamine residue of LCOs is due to the enzymatic activity of NodL. Here we show that transfer of the nodL gene into four rhizobial spec...

A well-resolved rhizobial species phylogeny with 51 haplotypes was inferred from a combined atpD + recA data set using Bayesian inference with best-fit, gene-specific substitution models. Relatively dense taxon sampling for the genera Rhizobium and Mesorhizobium was achieved by generating atpD and recA sequences for six type and 24 reference strains not previously available in GenBank. This phy...

Legumes form tripartite symbiotic associations with noduleinducing rhizobia and vesicular-arbuscular mycorrhizal fungi. Co-inoculation of soybean (Glycine max [L.] Merr.) roots with Bradyrhizobium japonicum 61-A-101 considerably enhanced colonization by the mycorrhizal fungus Glomus mosseae. A similar stimulatory effect on mycorrhizal colonization was also observed in nonnodulating soybean muta...

The tripartite symbiosis of common bean (Phaseolus vulgaris L.) recombinant inbred line (RIL) 147 with rhizobia and arbuscular mycorrhizal fungi (AMF) was assessed in sand culture by comparing the effects of three AMF species on the mycorrhizal root colonization, rhizobial nodulation, plant growth and phosphorus use efficiency for symbiotic nitrogen fixation. Although Glomus intraradices well c...

Samples of Rhizobium bacteroids isolated from pea nodule symbiosomes reacted positively with a monoclonal antibody recognizing N-linked glycan epitopes on plant glycoproteins associated with the peribacteroid membrane and peribacteroid fluid. An antiserum recognizing the symbiosomal lectin-like glycoprotein PsNLEC-1 also reacted positively. Samples of isolated bacteroids also reacted with an an...

Frankia sp. NRRL B-16219 was directly isolated from a soil sample obtained from the rhizosphere of Ceanothus jepsonii growing in the USA. Its host plant range includes members of Elaeagnaceae species. Phylogenetically, strain NRRL B-16219 is closely related to "Frankia discariae" with a 16S rRNA gene similarity of 99.78%. Because of the lack of genetic tools for Frankia, our understanding of th...

Twelve rhizobial isolates were recovered from nodules of common bean (Phaseolus vulgaris) grown in two different locations of Egyptian soils. The most effective strains for nodule formation and nitrogen fixation were selected. Strain specificity with the bean cultivars Saxa, Canoca and Giza 6 from Germany, Colombia and Egypt were studied. The strains were characterized by amplified rDNA restric...

Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT), perlite sugarcane bagasse (PSB), carboxymethyl cellulose plus starch (CMCS), and yeast extract mannitol supplemented wi...