Regulation and function of rhizobial nodulation genes

GOTTFERT, M

doi:10.1016/0378-1097(93)90503-t

Cited by 17 publications

(22 citation statements)

References 179 publications

(334 reference statements)

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“…Various so-called nod (for nodulation) genes play an essential role in the biosynthesis of the LCOs (7). Common to all rhizobia are the genes nodA, nodB, nodC, nodI, and nodJ, which are usually organized in one transcriptional unit which is regulated by plant flavonoids (5,12,22). The first three of these genes were shown to be sufficient for the biosynthesis of LCO molecules (28).…”

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confidence: 99%

Rhizobium NodI and NodJ proteins play a role in the efficiency of secretion of lipochitin oligosaccharides

1995

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Thin-layer chromatographic analysis of extracts of D-[1-14 C]glucosamine-labelled rhizobia was used to analyze the effects of nodI, nodJ, and nodT on secretion of lipochitin oligosaccharide (LCO) signal molecules. Secretion was analyzed by comparing quantitities of radiolabelled LCOs present in the cellular and spent growth medium fractions. A second rapid and sensitive method was introduced to estimate the secreted LCO fractions by using D-[1-14 C]glucosamine-labelled cells grown in medium supplemented with chitinase. At various times after induction of LCO synthesis, the quantity of degradation products of LCOs was compared with the amount of nondegraded LCOs. In wild-type strains of Rhizobium leguminosarum biovars viciae and trifolii the nodI and nodJ genes (but not the nodT gene) strongly enhance the secretion of LCOs during the first 5 h after the induction of LCO synthesis. In LCO-overproducing strains the enhancement of secretion was observed only during the first 3 h after induction. At times later than 5 h after induction, a significant influence of the presence of the nodI and nodJ genes on LCO secretion was detectable neither in the wild type nor in LCO-overproducing strains. By using plasmids in which the nodI and nodJ genes are cloned separately under control of a flavonoid-inducible promoter, it was shown that both genes are needed for a wild-type level of LCO secretion. Therefore, these results demonstrate that nodI and nodJ play a role in determining the efficiency of LCO secretion.

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confidence: 99%

Rhizobium NodI and NodJ proteins play a role in the efficiency of secretion of lipochitin oligosaccharides

1995

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“…and specific nodulation genes encode a variety of enzymes that are able to modify this basic core, making Nod factors plantspecific [4,5].…”

Section: Introductionmentioning

confidence: 99%

Rhizobium tropici nodulation factor sulfation is limited by the quantity of activated form of sulfate

et al. 1995

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“…The genus Rhizobium comprises a group of soil bacteria that form nodules on the roots and stems of legume host plants for symbiotic nitrogen fixation (Gottfert 1993). In legume nodules, rhizobia differentiate into bacteroids that are able to reduce atmospheric nitrogen to ammonia, which can be effectively used by host legume plants.…”

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confidence: 99%

NAD+-malic enzyme affects nitrogenase activity of Mesorhizobium loti bacteroids in Lotus japonicus nodules

Thapanapongworakul

Nomura

Shimoda

et al. 2010

Plant Biotechnology

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A gram-negative bacterium, Mesorhizobium loti, contains a NADP ϩ -malic enzyme (mlr5329) and a malate oxidoreductase (mlr0809) in the genome. We have screened transposon-induced mutants from the signature-tagged mutant library to survey their roles in nodule nitrogenase activity. The nodules induced by malate oxidoreductase mutants failed to fix N 2 , although NADP ϩ -malic enzyme (NADP ϩ -ME) mutants induced nodules exhibiting no change in nodule nitrogenase activity. When malate-degrading enzyme activities were compared between malate oxidoreductase mutants and wild-type M. loti, NAD ϩ -malic enzyme (NAD ϩ -ME) activity was decreased significantly in malate oxidoreductase mutants, suggesting it is an NAD ϩ -ME mutant. We found that NADP ϩ -ME was not required for N 2 fixation. The fact that significant accumulations of sucrose, starch granules and malate were observed in the nodules induced by malate oxidoreductase mutant suggests that low nitrogenase activity of the nodules resulted in photosynthate accumulation. These data suggest that this malate oxidoreductase has a similar function to NAD ϩ -ME in both Bradyrhizobium japonicum and Sinorhizobium meliloti. Plant Biotechnology 27, 311-316 (2010) Original Paper Transposon insertion mutants, generated using signature-tagged mutagenesis (STM), are a powerful technique that can be used to identify the genes required for symbiotic nitrogen fixation function in root nodules (Shimoda et al. 2008). We have selected STM mutants that had a transposon inserted in the malic enzyme genes from the collection of transposon mutants and studied the function of these genes. Key words: Lotus japonicus, Mesorhizobium loti, NAD Materials and methods Bacterial strains and mediaTransposon insertion mutants (STM mutant) of M. loti MAFF303099 were obtained from Kazusa DNA Research Institute (Shimoda et al. 2008). M. loti strains were cultured in tryptone-yeast extract (TY) liquid medium (Beringer 1974) at 28ºC. Antibiotics were added to the media in the following concentrations: spectinomycin 100 µg mL Ϫ1, streptomycin 100 µg mL -1 and phosphomycin 100 µg mL Ϫ1. Plant materialsSeeds of L. japonicus B-129 Gifu (Handberg and Stougaard 1992) were sterilized with a sodium hypochlorite solution, rinsed with sterile water, and allowed to germinate in sterile vermiculite with liquid B&D medium (Broughton and Dilwoth 1971) in double Magenda jars. Then 1ϫ10 9 cells mL Ϫ1 was added in the jars. These plants were grown in an artificially growth cabinet controlled at 22ºC (16 hr/8hr, light/dark). Acetylene reduction activityFor acetylene reduction activity, plants at 35 days after infection were used. The nodules were placed in a 20 ml vial and incubated at 25ºC by adding 2.6 ml of acetylene. After 30 min, the amount of ethylene formed was measured by gas chromatography (Shimazu GC-8A) to determine ethylene production as described previously (Kouchi et al. 1989) Light microscopyNodules were fixed in 4% paraformaldehyde and 25% glutaraldehyde in 0.5 M Sodium phosphate buffer (pH 7.2...

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Regulation and function of rhizobial nodulation genes

Cited by 17 publications

References 179 publications

Rhizobium NodI and NodJ proteins play a role in the efficiency of secretion of lipochitin oligosaccharides

Rhizobium NodI and NodJ proteins play a role in the efficiency of secretion of lipochitin oligosaccharides

Rhizobium tropici nodulation factor sulfation is limited by the quantity of activated form of sulfate

NAD+-malic enzyme affects nitrogenase activity of Mesorhizobium loti bacteroids in Lotus japonicus nodules

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