Fuel remains in archaeological context: expirimental and archaeological evidence for recognizing remains in hearts used by Iron Age farmers who lived in peatlands

Plant science

Bacteriocin small of Fast-growing rhizobia is chloroform soluble and is not required for effective nodulation

Microbial Biotechnolog

Lipochitin oligosaccharides from Rhizobium leguminosarum bv. viciae reduce auxin transport n capacity in Vicia sativa subsp. nigra roots

Microbial Biotechnolog

Induction of the nodA promoter Rhizobium leguminosarum Sym plasmid pRL1JI by plant flavanones and flavones

An expression vector containing the Rhizobium leguminosarum nodA promoter cloned in front of the Escherichia coli lacZ gene was used to characterize the properties of the R. leguminosarum nodA gene-inducing compound(s) present in sterile root exudate of the host plant Vicia sativa L. subsp. nigra (L.). The major inducing compound was flavonoid in nature, most likely a flavanone. The commercially available flavonoids naringenin (5,7,4'-trihydroxyflavanone), eriodictyol (5,7,3'4'-tetrahydroxyflavanone), apigenin (5,7,4'-trihydroxyflavone), and luteolin (5,7,3',4'-tetrahydroxyflavone) induced the nodA promoter to the same level as the root exudate. On the basis of chromatographic properties, it was concluded that none of these compounds is identical to the inducer that is present in root exudate. The induction of the nodA promoter by root exudate and by the most effective inducer naringenin was very similar, as judged from the genetic requirements and the kinetics of induction.Plant sciencesBio-organic SynthesisMicrobial Biotechnolog

Plant-inducible virulence promoter of the Agrobacterium tumefaciens Ti plasmid

Microbial Biotechnolog

Expression of a rhizobium phaseoli sym plasmid in R. trifolii and agrobacterium tumefaciens: incompatibility with a R. trifolii sym plasmid

Microbial BiotechnologyPlant science

Role of plant root exudate and Sym plasmid-localized nodulation genes in the synthesis by Rhizobium leguminosarum of Tsr factor, which causes thick and short roots on common vetch

Microbial Biotechnolog

Rhizobium leguminosarum bv. trifolii produces Lipo-chitin oligosaccharides with nodE-dependent highly unsaturated fatty acyl moieties. An electrospray ionization and collision-induced dissociation tandem mass spectrometric study

Microbial Biotechnolog

Host specificity of Rhizobium leguminosarum is determined by the hydrophobicity of highly unsaturated fatty acyl moieties of the nodulation factors

The nodE genes of Rhizobium leguminosarum bvs, trifolii and viciae strains are the major determinants of the host range of nodulation, Using mass spectrometry we have analyzed the structures of the major and minor lipooligosaccharides produced by two R, leguminosarum strains that differ only in the origin of the nod genes, The strain containing the nod genes of R. l. by. viciae produces lipo-chitin oligosaccharide (LCO) molecules that contain the common cis-vaccenyl (C18:1) or a highly unsaturated acyl (C18:4) group that is determined by nodE (Spaink et al, Nature 354:125-130, 1991), Here we show that, in addition, minor quantities of analogous molecules that contain different common fatty acyl groups such as stearyl (C18:0), palmityl (C16:0), and palmitoyl (C16:1) groups are produced, The set of LCOs produced by the strain containing the R. l. by. trifolii nod genes is similar, but major differences are found in the length and unsaturation of the fatty acyl groups of various LCOs. The R. l, by. trifolii strain does not produce LCO molecules that contain the C18:4 fatty acyl group. Instead, a complex mixture of other unsaturated fatty acyl groups containing either two, three, or four double bonds is produced, These novel fatty acyl groups are more hydrophobic than the C18:4 fatty acyl group found in by. viciae, as judged by highperformance liquid chromatography retention times, probably as a result of the longer carbon chain length, the lack of a cis double bond, or both, Another difference is that the relative amount of highly unsaturated fatty acid-containing LCOs produced by R. l. by. trifolii is much smaller An isogenic R. l. by. trifolii strain containing a Tn5 insertion in the nodE gene only produces LCOs containing the common fatty acyl groups and not the highly unsaturated types, The results indicate that the difference in the host range of the R. l. bvs, viciae and trifolii is determined by the overall hydrophobicity of the highly unsaturated fatty acyl moieties of LCOs rather than by a specific structural feature.Microbial Biotechnolog

Role of rhizobial lipo-oligosacharides in root nodule formation on leguminious plants

Microbial Biotechnolog