Biomaterial Database

Two plasmids other than the nodulation plasmid are necessary for formation of nitrogen-fixing nodules by Rhizobium leguminosarum. 1990

M F Hynes, and N F McGregor

Soil Science Section, Agriculture Canada Research Station, Lethbridge, Alberta.

A system which allows direct selection for curing of plasmids in Gram-negative bacteria was used to generate derivatives of Rhizobium leguminosarum VF39 cured of each of six plasmids present in this strain. Phenotypes could be correlated with the absence of five of the six plasmids. The smallest plasmid, pRleVF39a, carries genes for the production of a melanin-like pigment as has been previously reported. Plasmid pRleVF39d carries nodulation and nitrogen fixation genes. Curing of the plasmids pRleVF39c and pRleVF39e gave rise to strains which formed Fix- nodules on peas, lentils, and faba beans. The nodules formed by the strains cured of pRleVF39c contained few, if any, bacteria. Analysis of washed cells by SDS-PAGE showed that this strain is defective in lipopolysaccharide (LPS) production; the defect could be complemented by introducing plasmids from several other R. leguminosarum strains, and by the R. leguminosarum biovar phaseoli LPS gene clones pCos126 and pDel27. The nodules formed by the strain cured of pRleVF39e had a reduced symbiotic zone, an enlarged senescence zone, and an abundance of starch granules. This strain grew at a much slower rate than the wild type, was unable to grow on minimal medium, and no longer produced melanin. These defects could be complemented by at least one other Rhizobium plasmid, pRle336e, a plasmid of strain 336 which is distinct from the nodulation plasmid (pRle336c) and the plasmid (pRle336d) which could complement the LPS defect associated with the loss of pRleVF39c. This demonstrates that genes necessary for symbiosis can be carried on at least three different plasmids in R. leguminosarum.

UI	MeSH Term	Description	Entries
D007887	Fabaceae	The large family of plants characterized by pods. Some are edible and some cause LATHYRISM or FAVISM and other forms of poisoning. Other species yield useful materials like gums from ACACIA and various LECTINS like PHYTOHEMAGGLUTININS from PHASEOLUS. Many of them harbor NITROGEN FIXATION bacteria on their roots. Many but not all species of "beans" belong to this family.	Afzelia,Amorpha,Andira,Baptisia,Callerya,Ceratonia,Clathrotropis,Colophospermum,Copaifera,Delonix,Euchresta,Guibourtia,Legumes,Machaerium,Pithecolobium,Stryphnodendron,Leguminosae,Pea Family,Pithecellobium,Tachigalia,Families, Pea,Family, Pea,Legume,Pea Families
D008070	Lipopolysaccharides	Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)	Lipopolysaccharide,Lipoglycans
D009586	Nitrogen Fixation	The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.	Diazotrophy,Diazotrophic Activity,Dinitrogen Fixation,N2 Fixation,Activities, Diazotrophic,Activity, Diazotrophic,Diazotrophic Activities,Fixation, Dinitrogen,Fixation, N2,Fixation, Nitrogen
D010641	Phenotype	The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.	Phenotypes
D010946	Plants, Medicinal	Plants whose roots, leaves, seeds, bark, or other constituent parts possess therapeutic, tonic, purgative, curative or other pharmacologic attributes, when administered to man or animals.	Herbs, Medicinal,Medicinal Herbs,Healing Plants,Medicinal Plants,Pharmaceutical Plants,Healing Plant,Herb, Medicinal,Medicinal Herb,Medicinal Plant,Pharmaceutical Plant,Plant, Healing,Plant, Medicinal,Plant, Pharmaceutical,Plants, Healing,Plants, Pharmaceutical
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D004251	DNA Transposable Elements	Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.	DNA Insertion Elements,DNA Transposons,IS Elements,Insertion Sequence Elements,Tn Elements,Transposable Elements,Elements, Insertion Sequence,Sequence Elements, Insertion,DNA Insertion Element,DNA Transposable Element,DNA Transposon,Element, DNA Insertion,Element, DNA Transposable,Element, IS,Element, Insertion Sequence,Element, Tn,Element, Transposable,Elements, DNA Insertion,Elements, DNA Transposable,Elements, IS,Elements, Tn,Elements, Transposable,IS Element,Insertion Element, DNA,Insertion Elements, DNA,Insertion Sequence Element,Sequence Element, Insertion,Tn Element,Transposable Element,Transposable Element, DNA,Transposable Elements, DNA,Transposon, DNA,Transposons, DNA
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D005816	Genetic Complementation Test	A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.	Allelism Test,Cis Test,Cis-Trans Test,Complementation Test,Trans Test,Allelism Tests,Cis Tests,Cis Trans Test,Cis-Trans Tests,Complementation Test, Genetic,Complementation Tests,Complementation Tests, Genetic,Genetic Complementation Tests,Trans Tests
D012231	Rhizobium	A genus of gram-negative, aerobic, rod-shaped bacteria that activate PLANT ROOT NODULATION in leguminous plants. Members of this genus are nitrogen-fixing and common soil inhabitants.