scholarly journals Phaseolus vulgaris Recognizes Azorhizobium caulinodans Nod Factors with a Variety of Chemical Substituents

1999 ◽  
Vol 12 (9) ◽  
pp. 820-824 ◽  
Author(s):  
T. Laeremans ◽  
C. Snoeck ◽  
J. Mariën ◽  
C. Verreth ◽  
E. Martínez-Romero ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Host Plant ◽  
Wide Spectrum ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Rhizobium Tropici ◽  
Nod Factor ◽  
Mutant Strains

Phaseolus vulgaris is a promiscuous host plant that can be nodulated by many different rhizobia representing a wide spectrum of Nod factors. In this study, we introduced the Rhizobium tropici CFN299 Nod factor sulfation genes nodHPQ into Azorhizobium caulinodans. The A. caulinodans transconjugants produce Nod factors that are mostly if not all sulfated and often with an arabinosyl residue as the reducing end glycosylation. Using A. caulinodans mutant strains, affected in reducing end decorations, and their respective transconjugants in a bean nodulation assay, we demonstrated that bean nodule induction efficiency, in decreasing order, is modulated by the Nod factor reducing end decorations fucose, arabinose or sulfate, and hydrogen.

Regulation of Nod factor sulphation genes in Rhizobium tropici CIAT899

2001 ◽  
Vol 47 (6) ◽  
pp. 574-579 ◽  
Author(s):  
Hamid Manyani ◽  
Carolina Sousa ◽  
María-Eugenia Soria Díaz ◽  
Antonio Gil-Serrano ◽  
Manuel Megías
Keyword(s):  
Wide Spectrum ◽  
Constitutive Expression ◽  
Upstream Region ◽  
Broad Host Range ◽  
Nod Factors ◽  
Rhizobium Tropici ◽  
Free Living ◽  
Nod Factor ◽  
Symbiotic Plasmid ◽  
Transcriptional Fusions

Rhizobium tropici CIAT899 is a tropical symbiont able to nodulate various legumes such as Leucaena, Phaseolus, and Macroptilium. Broad host range of this species is related to its Nod factors wide spectrum. R. tropici contains Nod factors sulphation nod genes, nodHPQ genes, which control nodulation efficiency in Leucaena. To study nodHPQ regulation, we carried out different interposon insertions in its upstream region. One of these generated interruptions, nodI mutant produced nonsulphated Nod factors suggesting a possible dependence of these genes on nodI upstream region. Moreover, analysis results of lacZ transcriptional fusions with these genes in symbiotic plasmid showed dependence of these genes on NodD protein. In order to determine nodHPQ organization, we studied the effect of interposon insertion upstream of each lacZ transcriptional fusion, and the data obtained was used to indicate that nodHPQ belong to the nodABCSUIJ operon. However, comparison between nodP::lacZ β-galactosidase activity in the symbiotic plasmid and in the pHM500 plasmid (containing nodHPQ genes) suggested constitutive expression in free living, and flavonoid inducible expression in symbiotic conditions. Constitutive nodHPQ expression may play a role in bacterial house-keeping metabolism. On the other hand, the transference of R. tropici nodHPQ genes to other rhizobia that do not present sulphated substitutions demonstrated that NodH protein sulphotransference is specific to C6 at the reducing end.Key words: Nod factors, nodHPQ genes, Rhizobium tropici, nod-box.

Root nodulation of Sesbania rostrata suppresses stem nodulation by Sinorhizobium teranga but not Azorhizobium caulinodans

1996 ◽  
Vol 42 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Kodjo Tomekpe ◽  
Marcelle Holsters ◽  
Bernard Dreyfus
Keyword(s):  
Host Plant ◽  
Root Nodules ◽  
Sesbania Rostrata ◽  
Efficient Production ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Experimental Conditions ◽  
Nod Factor ◽  
Stem Nodulation ◽  
Azorhizobium Caulinodans Ors571

Azorhizobium caulinodans ORS571 and Sinorhizobium teranga ORS51 and ORS52 are symbionts of the same host plant Sesbania rostrata. In nature, A. caulinodans nodulates more competitively the stem-located infection sites of Sesbania rostrata. Sinorhizobium strains, although frequently present in root nodules, are seldom found in stem nodules. One probable explanation for this phenomenon is the more abundant presence of Azorhizobium on the leaf and stem surfaces of the host plant. Work presented here hints at other plausible factors that determine the greater "stem specificity" of Azorhizobium. We found that under experimental conditions in which roots are not inoculated, all strains nodulated stems very well. However, ORS51 and ORS52 were much more sensitive than ORS571 to suppression of stem nodulation by previous root inoculation. The introduction of the regulatory nodD gene from A. caulinodans diminished the sensitivity to this suppression, probably by enhanced nod gene expression and subsequent Nod factor production. Our hypothesis is that the greater infectivity of ORS571 is due to a more efficient production of mitogenic Nod factors at stem-located infection sites, thereby more readily overcoming systemic suppression caused by previous root inoculations.Key words: autoregulation, nitrogen fixation, rhizobial ecology, systemic suppression of nodulation.

scholarly journals Sulfation of Nod Factors via nodHPQ Is nodD Independent in Rhizobium tropici CIAT899

1998 ◽  
Vol 11 (10) ◽  
pp. 979-987 ◽  
Author(s):  
Jorge Luis Folch-Mallol ◽  
Hamid Manyani ◽  
Silvia Marroquí ◽  
Carolina Sousa ◽  
Carmen Vargas ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Leucaena Leucocephala ◽  
Regulatory Region ◽  
Constitutive Expression ◽  
Nod Factors ◽  
Rhizobium Tropici ◽  
Independent Manner ◽  
Macroptilium Atropurpureum ◽  
Tlc Analysis ◽  
Layer Chromatography

A cosmid from the Rhizobium tropici CIAT899 symbiotic plasmid, containing most of the nodulation genes described in this strain, has been isolated. Although this cosmid does not carry a nodD gene, it confers ability to heterologous Rhizobium spp. to nodulate R. tropici hosts (Phaseolus vulgaris, Macroptilium atropurpureum, and Leucaena leucocephala). The observed phenotype is due to constitutive expression of the nodABCSUIJ operon, which has lost its regulatory region and is expressed from a promoter present in the cloning vector. Thin-layer chromatography (TLC) analysis of the Nod factors produced by this construction shows that it is still capable of synthesizing sulfated compounds, suggesting that the nodHPQ genes are organized as an operon that is transcribed in a nodD-independent manner and is not regulated by flavonoids. Se ha aislado un cósmido del plásmido simbiótico de Rhizobium tropici CIAT899 que contiene la mayoría de los genes de nodulación descrito para esta estirpe, menos el gen regulador nodD. La introducción de este cósmido en una estirpe curada del plásmido simbiótico de R. tropici CIAT899 permite la nodulación en las plantas ensayadas (Phaseolus vulgaris, Macroptilium atropurpureum, y Leucaena leucocephala). El fenotipo observado se debe a la expresión constitutiva del operón nodABCSUIJ bajo el promotor del gen de resistencia a la kanamicina, que lleva el vector donde se ha clonado el fragmento de ADN. Análisis por cromatografia de capa fina demuestran que esta construcción es capaz de sulfatar el extremo reductor del factor Nod. Estas evidencias sugieren que los genes nodHPQ constituyen un operón, y que su expresión es independiente del gen regulador nodD.

scholarly journals High-Affinity Nod Factor Binding Site from Phaseolus vulgaris Cell Suspension Cultures

2002 ◽  
Vol 15 (8) ◽  
pp. 834-839 ◽  
Author(s):  
Frédéric Gressent ◽  
Natacha Mantegazza ◽  
Julie V. Cullimore ◽  
Hugues Driguez ◽  
Raoul Ranjeva ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Binding Site ◽  
Acyl Chain ◽  
Minor Role ◽  
Nod Factors ◽  
Nod Factor ◽  
Factor Binding Site ◽  
Factor Binding ◽  
High Affinity ◽  
Perception System

The lipo-chitooligosaccharidic Nod factors produced by rhizobia are key molecules in the establishment of symbiosis with legumes and probably are recognized by the host plant via specific receptors. Here, we report on the presence of a binding site in cell cultures of Phaseolus vulgaris displaying a high affinity for Nod factors from Rhizobium tropici (NodRt-V) (Me, S, C18:1), a symbiont of this legume. The binding site shares common properties with NFBS2, a Nod-factor binding site previously characterised in Medicago varia, in terms of affinity, preferential plasma-membrane location, and sensitivity to proteases and lysine reactive reagents. However, the bean site poorly recognizes the Nod factors produced by Sinorhizobium meliloti, the symbiont of Medicago. The study of selectivity toward the Nod factors reveals that the length and degree of unsaturation of the acyl chain and the length of the oligosaccharidic moiety are important determinants of high affinity binding to the bean site; whereas, the N-methyl and O-sulfuryl groups play a minor role. Thus, the common characteristics of P. vulgaris and M. varia Nod-factor binding sites suggest that they probably correspond to structurally related proteins, but their different selectivity suggests that they may be involved in a differential perception system for Nod factors in legumes.

scholarly journals Rhizobium-Induced Calcium Spiking in Lotus japonicus

2003 ◽  
Vol 16 (4) ◽  
pp. 335-341 ◽  
Author(s):  
Jeanne M. Harris ◽  
Rebecca Wais ◽  
Sharon R. Long
Keyword(s):  
Host Plant ◽  
Lotus Japonicus ◽  
Developmental Changes ◽  
Nodule Development ◽  
Cytoplasmic Calcium ◽  
Nod Factors ◽  
Developmental Pathway ◽  
Nod Factor ◽  
Calcium Spiking ◽  
General Component

Legumes and rhizobium bacteria form a symbiosis that results in the development of nitrogen-fixing nodules on the root of the host plant. The earliest plant developmental changes are triggered by bacterially produced nodulation (Nod) factors. Within minutes of exposure to Nod factors, sharp oscillations in cytoplasmic calcium levels (calcium spiking) occur in epidermal cells of several closely related legumes. We found that Lotus japonicus, a legume that follows an alternate developmental pathway, responds to both its bacterial partner and to the purified bacterial signal with calcium spiking. Thus, calcium spiking is not restricted to a particular pathway of nodule development and may be a general component of the response of host legumes to their bacterial partner. Using Nod factor-induced calcium spiking as a tool to identify mutants blocked early in the response to Nod factor, we show that the L. japonicus Ljsym22-1 mutant but not the Ljsym30 mutant fails to respond to Nod factor with calcium spiking.

scholarly journals Nod Factors of Azorhizobium caulinodans Strain ORS571 Can Be Glycosylated with an Arabinosyl Group, a Fucosyl Group, or Both

1997 ◽  
Vol 10 (5) ◽  
pp. 683-687 ◽  
Author(s):  
Peter Mergaert ◽  
Myriam Ferro ◽  
Wim D'Haeze ◽  
Marc Van Montagu ◽  
Marcelle Holsters ◽  
...  
Keyword(s):  
Relative Proportion ◽  
Growth Conditions ◽  
Sesbania Rostrata ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Nod Factor ◽  
Nod Genes ◽  
Group A ◽  
Root Hair Formation ◽  
Hair Formation

In addition to the previously described arabinosylated Nod factors, Azorhizobium caulinodans can also produce fucosylated Nod factors and Nod factors that are both arabinosylated and fucosylated. The presence of a plasmid carrying extra copies of a subset of nod genes as well as bacterial growth conditions influence the relative proportion of carbamoylated, fucosylated, and arabinosylated Nod factors. By using a root hair formation assay, we demonstrate that the Nod factor glycosylations are important for biological activity on Sesbania rostrata roots.

scholarly journals Genes Essential for Nod Factor Production and Nodulation Are Located on a Symbiotic Amplicon (AMPRtrCFN299pc60) in Rhizobium tropici

1998 ◽  
Vol 180 (11) ◽  
pp. 2866-2874 ◽  
Author(s):  
Patrick Mavingui ◽  
Toon Laeremans ◽  
Margarita Flores ◽  
David Romero ◽  
Esperanza Martínez-Romero ◽  
...  
Keyword(s):  
Insertion Sequence ◽  
Gene Dosage ◽  
Kanamycin Resistance ◽  
Nod Factors ◽  
Rhizobium Tropici ◽  
Resistance Marker ◽  
Nod Factor ◽  
Origins Of Replication ◽  
Symbiotic Plasmid

ABSTRACT Amplifiable DNA regions (amplicons) have been identified in the genome of Rhizobium etli. Here we report the isolation and molecular characterization of a symbiotic amplicon of Rhizobium tropici. To search for symbiotic amplicons, a cartridge containing a kanamycin resistance marker that responds to gene dosage and conditional origins of replication and transfer was inserted in the nodulation region of the symbiotic plasmid (pSym) of R. tropici CFN299. Derivatives harboring amplifications were selected by increasing the concentration of kanamycin in the cell culture. The amplified DNA region was mobilized into Escherichia coli and then into Agrobacterium tumefaciens. The 60-kb symbiotic amplicon, which we termed AMPRtrCFN299pc60, contains several nodulation and nitrogen fixation genes and is flanked by a novel insertion sequence ISRtr1. Amplification of AMPRtrCFN299pc60 through homologous recombination between ISRtr1 repeats increased the amount of Nod factors. Strikingly, the conjugal transfer of the amplicon into a plasmidlessA. tumefaciens strain confers on the transconjugant the ability to produce R. tropici Nod factors and to nodulatePhaseolus vulgaris, indicating that R. tropicigenes essential for the nodulation process are confined to an ampliable DNA region of the pSym.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Sexuality in Neurospora crassa I. Mutations to male sterility

1972 ◽  
Vol 19 (3) ◽  
pp. 191-204 ◽  
Author(s):  
J. Weijer ◽  
N. V. Vigfusson
Keyword(s):  
Neurospora Crassa ◽  
Male Sterility ◽  
Wide Spectrum ◽  
Female Parent ◽  
Behaviour Pattern ◽  
Type Locus ◽  
Development Cycle ◽  
Ultraviolet Light Irradiation ◽  
Mutant Strains ◽  
Aberrant Segregation

SUMMARYMutations giving rise to sexual sterility were induced in Neurospora crassa macroconidia by ultraviolet-light irradiation. Thirty mutants were isolated on the basis of their male sterility in crosses with a wild-type strain. When used as the male parent these mutants exhibited a wide spectrum of sexual behaviour patterns ranging from the production of only small brown protoperithecia (complete male sterility) to the production of large and normally pigmented perithecia but with an undeveloped ostiole and very few if any spores. For many of the mutants the behaviour pattern is different when the strain is used as the female parent. Segregation data reveal that none of these mutants represent mutations of the mating-type locus. These findings suggest that the sexual development cycle is blocked at various stages in the different mutant strains. All attempts to restore fertility by supplying various additives to the medium or by varying the incubation time and temperature were unsuccessful. Conidial viability tests carried out on many of the strains revealed no abnormality in this respect. The aberrant segregation patterns exhibited by many of the mutants are discussed.

scholarly journals Rhizobium tropici Genes Involved in Free-Living Salt Tolerance are Required for the Establishment of Efficient Nitrogen-Fixing Symbiosis with Phaseolus vulgaris

2002 ◽  
Vol 15 (3) ◽  
pp. 225-232 ◽  
Author(s):  
Joaquina Nogales ◽  
Rosario Campos ◽  
Hanaa BenAbdelkhalek ◽  
José Olivares ◽  
Carmen Lluch ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Phaseolus Vulgaris ◽  
Environmental Changes ◽  
Nitrogenase Activity ◽  
Regulation Of Gene Expression ◽  
Elongation Factor ◽  
Regulatory System ◽  
Trna Synthetase ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici

Characterization of nine transposon-induced mutants of Rhizobium tropici with decreased salt tolerance (DST) allowed the identification of eight gene loci required for adaptation to high external NaCl. Most of the genes also were involved in adaptation to hyperosmotic media and were required to overcome the toxicity of LiCl. According to their possible functions, genes identified could be classified into three groups. The first group included two genes involved in regulation of gene expression, such as ntrY, the sensor element of the bacterial ntrY/ntrX two-component regulatory system involved in regulation of nitrogen metabolism, and greA, which encodes a transcription elongation factor. The second group included genes related to synthesis, assembly, or maturation of proteins, such as alaS coding for alanine-tRNA synthetase, dnaJ, which encodes a molecular chaperone, and a nifS homolog probably encoding a cysteine desulfurase involved in the maturation of Fe-S proteins. Genes related with cellular build-up and maintenance were in the third group, such as a noeJ-homolog, encoding a mannose-1-phosphate guanylyltransferase likely involved in lipopolysaccharide biosynthesis, and kup, specifying an inner-membrane protein involved in potassium uptake. Another gene was identified that had no homology to known genes but that could be conserved in other rhizobia. When inoculated on Phaseolus vulgaris growing under nonsaline conditions, all DST mutants displayed severe symbiotic defects: ntrY and noeJ mutants were impaired in nodulation, and the remaining mutants formed symbiosis with very reduced nitrogenase activity. The results suggest that bacterial ability to adapt to hyper-osmotic and salt stress is important for the bacteroid nitrogen-fixing function inside the legume nodule and provide genetic evidence supporting the suggestion that rhizobia face severe environmental changes after their release into plant cells.

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