scholarly journals Involvement of Salicylic Acid in the Establishment of the Rhizobium meliloti-Alfalfa Symbiosis

1998 ◽  
Vol 11 (2) ◽  
pp. 153-155 ◽  
Author(s):  
F. Martínez-Abarca ◽  
J. A. Herrera-Cervera ◽  
P. Bueno ◽  
J. Sanjuan ◽  
T. Bisseling ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Rhizobium Meliloti ◽  
Significant Inhibition ◽  
Nod Factors ◽  
Wild Type ◽  
Nod Factor ◽  
Rhizobium Strains ◽  
Meliloti Strain

Inoculation of alfalfa plants with either incompatible Rhizobium or a Rhizobium mutant blocked in Nod factor synthesis led to an accumulation of salicylic acid in roots, in contrast to plants inoculated with a wild-type (compatible) R. meliloti strain. When salicylic acid was exogenously applied prior to inoculation of alfalfa plants with either purified Nod factor or compatible Rhizobium strains, a significant inhibition of nodule primordia formation and a reduction of the number of emerging nodules, respectively, as well as a delay in nodule visualization, were observed. These results suggest an involvement of Rhizobium-synthesized Nod factors in the inhibition of salicylic acid-mediated defense in legumes.

scholarly journals Identification of a Third Sulfate Activation System in Sinorhizobium sp. Strain BR816: the CysDN Sulfate Activation Complex

2003 ◽  
Vol 69 (4) ◽  
pp. 2006-2014 ◽  
Author(s):  
Carla Snoeck ◽  
Christel Verreth ◽  
Ismael Hernández-Lucas ◽  
Esperanza Martínez-Romero ◽  
Jos Vanderleyden
Keyword(s):  
Growth Characteristics ◽  
Open Reading Frames ◽  
Lag Phase ◽  
Sulfur Source ◽  
Nod Factors ◽  
Wild Type ◽  
Triple Mutant ◽  
Nod Factor ◽  
Growth Defects ◽  
Sulfate Activation

ABSTRACT Sinorhizobium sp. strain BR816 possesses two nodPQ copies, providing activated sulfate (3′-phosphoadenosine-5′-phosphosulfate [PAPS]) needed for the biosynthesis of sulfated Nod factors. It was previously shown that the Nod factors synthesized by a nodPQ double mutant are not structurally different from those of the wild-type strain. In this study, we describe the characterization of a third sulfate activation locus. Two open reading frames were fully characterized and displayed the highest similarity with the Sinorhizobium meliloti housekeeping ATP sulfurylase subunits, encoded by the cysDN genes. The growth characteristics as well as the levels of Nod factor sulfation of a cysD mutant (FAJ1600) and a nodP1 nodQ2 cysD triple mutant (FAJ1604) were determined. FAJ1600 shows a prolonged lag phase only with inorganic sulfate as the sole sulfur source, compared to the wild-type parent. On the other hand, FAJ1604 requires cysteine for growth and produces sulfate-free Nod factors. Apigenin-induced nod gene expression for Nod factor synthesis does not influence the growth characteristics of any of the strains studied in the presence of different sulfur sources. In this way, it could be demonstrated that the “household” CysDN sulfate activation complex of Sinorhizobium sp. strain BR816 can additionally ensure Nod factor sulfation, whereas the symbiotic PAPS pool, generated by the nodPQ sulfate activation loci, can be engaged for sulfation of amino acids. Finally, our results show that rhizobial growth defects are likely the reason for a decreased nitrogen fixation capacity of bean plants inoculated with cysD mutant strains, which can be restored by adding methionine to the plant nutrient solution.

The preference for strains of Rhizobium meliloti by cultivars of Medicago sativa grown on agar

1984 ◽  
Vol 30 (9) ◽  
pp. 1179-1183 ◽  
Author(s):  
E. S. P. Bromfield
Keyword(s):  
Antibiotic Resistance ◽  
Medicago Sativa ◽  
Parent Strain ◽  
Host Preference ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Rhizobium Strains ◽  
Axenic Conditions ◽  
Wild Type Parent

Variation in nodulation preference within and between cultivars of Medicago sativa for Rhizobium strains was assessed under axenic conditions using inocula consisting of paired strains of R. meliloti which could be recognized by distinctive colony morphology or antibiotic resistance. The largest variability in host preference for Rhizobium strains was among plants within cultivars and not between cultivars. The implications of such variation are discussed in the context of possible enhancement of symbiotic nitrogen fixation. An isolate of R. meliloti which had been marked with antibiotic resistance and cured of a cryptic plasmid was significantly less successful in nodulation than its wild-type parent strain in all inoculated combinations. The interaction of inoculum and cultivar on yield indicated differential symbiotic effectiveness of strains of R. meliloti on cultivars of M. sativa.

scholarly journals Role of the K-Antigen Subgroup of Capsular Polysaccharides in the Early Recognition Process Between Rhizobium meliloti and Alfalfa Leaves

1997 ◽  
Vol 10 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Isabelle Becquart-de Kozak ◽  
Bradley L. Reuhs ◽  
Dominique Buffard ◽  
Colette Breda ◽  
John S. Kim ◽  
...  
Keyword(s):  
Rhizobium Meliloti ◽  
Early Recognition ◽  
Wild Type ◽  
Transcript Accumulation ◽  
Bacterial Surface ◽  
Rapid Induction ◽  
Genes Encoding ◽  
Plant Genes ◽  
Meliloti Strain ◽  
Isoflavone Reductase

We used a model system to investigate the induction of plant genes by bacterial surface compounds. We have infiltrated alfalfa leaves with wild-type Rhizobium meliloti strain Rm41 and mutant derivatives, which are deficient in the production of exopolysaccharides (EPS), capsular K-polysaccharides (KPS or K-Antigens), or both. We have shown that wild-type R. meliloti was able to induce transcript accumulation of genes encoding enzymes of the iso-flavonoid biosynthetic pathway: chalcone synthase (CHS), chalcone reductase (CHR), and isoflavone reductase (IFR). Kinetics of these transcript accumulations were biphasic, occurring 0.75 to 1.5 h and 6 to 30 h after treatment. The exoB derivative of Rm41 (strain AK631), which is unable to produce either EPS I or EPS II, was still able to induce very rapid (45-min posttreatment) transcript accumulation of CHS and CHR genes. These results suggested that EPS were not involved in this induction. We then tested three R. meliloti fix-23 mutants (strains PP699, PP711, and PP671), which were deficient in KPS production as shown by PAGE and immunoblot analyses. In contrast to the results obtained with the mutant strains, infiltration of alfalfa leaves with purified KPS, isolated from strain AK631, led to a very rapid induction of the CHS and CHR genes. Therefore, we hypothesize that KPS may play a role in the early recognition of rhizobia by the leaf cells.

scholarly journals Salicylic Acid Accumulation Controlled by LSD1 Is Essential in Triggering Cell Death in Response to Abiotic Stress

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 962
Author(s):  
Maciej Jerzy Bernacki ◽  
Anna Rusaczonek ◽  
Weronika Czarnocka ◽  
Stanisław Karpiński
Keyword(s):  
Cell Death ◽  
Salicylic Acid ◽  
Abiotic Stress ◽  
Wild Type ◽  
Pr Genes ◽  
Genes Expression ◽  
Salicylic Acid Accumulation ◽  
Cell Death Phenotype ◽  
Insight Into

Salicylic acid (SA) is well known hormonal molecule involved in cell death regulation. In response to a broad range of environmental factors (e.g., high light, UV, pathogens attack), plants accumulate SA, which participates in cell death induction and spread in some foliar cells. LESION SIMULATING DISEASE 1 (LSD1) is one of the best-known cell death regulators in Arabidopsis thaliana. The lsd1 mutant, lacking functional LSD1 protein, accumulates SA and is conditionally susceptible to many biotic and abiotic stresses. In order to get more insight into the role of LSD1-dependent regulation of SA accumulation during cell death, we crossed the lsd1 with the sid2 mutant, caring mutation in ISOCHORISMATE SYNTHASE 1(ICS1) gene and having deregulated SA synthesis, and with plants expressing the bacterial nahG gene and thus decomposing SA to catechol. In response to UV A+B irradiation, the lsd1 mutant exhibited clear cell death phenotype, which was reversed in lsd1/sid2 and lsd1/NahG plants. The expression of PR-genes and the H2O2 content in UV-treated lsd1 were significantly higher when compared with the wild type. In contrast, lsd1/sid2 and lsd1/NahG plants demonstrated comparability with the wild-type level of PR-genes expression and H2O2. Our results demonstrate that SA accumulation is crucial for triggering cell death in lsd1, while the reduction of excessive SA accumulation may lead to a greater tolerance toward abiotic stress.

scholarly journals Uncoupling Salicylic Acid-Dependent Cell Death and Defense-Related Responses From Disease Resistance in the Arabidopsis Mutant acd5

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 341-350
Author(s):  
Jean T Greenberg ◽  
F Paul Silverman ◽  
Hua Liang
Keyword(s):  
Cell Death ◽  
Salicylic Acid ◽  
Disease Resistance ◽  
Pseudomonas Syringae ◽  
Higher Plants ◽  
Ethylene Signaling ◽  
Symptom Development ◽  
Wild Type ◽  
Dependent Cell ◽  
Arabidopsis Mutant

Abstract Salicylic acid (SA) is required for resistance to many diseases in higher plants. SA-dependent cell death and defense-related responses have been correlated with disease resistance. The accelerated cell death 5 mutant of Arabidopsis provides additional genetic evidence that SA regulates cell death and defense-related responses. However, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to Pseudomonas syringae early in development and show spontaneous SA accumulation, cell death, and defense-related markers later in development. In acd5 plants, cell death and defense-related responses are SA dependent but they do not confer disease resistance. Double mutants with acd5 and nonexpressor of PR1, in which SA signaling is partially blocked, show greatly attenuated cell death, indicating a role for NPR1 in controlling cell death. The hormone ethylene potentiates the effects of SA and is important for disease symptom development in Arabidopsis. Double mutants of acd5 and ethylene insensitive 2, in which ethylene signaling is blocked, show decreased cell death, supporting a role for ethylene in cell death control. We propose that acd5 plants mimic P. syringae-infected wild-type plants and that both SA and ethylene are normally involved in regulating cell death during some susceptible pathogen infections.

scholarly journals Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms

2014 ◽  
Vol 307 (9) ◽  
pp. G941-G949 ◽  
Author(s):  
Padmanabhan Srinivasan ◽  
Rubina Kapadia ◽  
Arundhati Biswas ◽  
Hamid M. Said
Keyword(s):  
Transgenic Mice ◽  
Chronic Exposure ◽  
Methylation Status ◽  
Acinar Cells ◽  
Alcohol Exposure ◽  
Significant Inhibition ◽  
Pancreatic Acinar Cells ◽  
Chronic Alcohol ◽  
Wild Type ◽  
Chronic Alcohol Exposure

Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5′-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na+ dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.

Expression of the nodulation and nitrogen fixation genes in Rhizobium meliloti during development

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 354-360 ◽  
Author(s):  
San Chiun Shen ◽  
Shui Ping Wang ◽  
Guan Qiao Yu ◽  
Jia Bi Zhu
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Abnormal Development ◽  
Wild Type ◽  
Free Living ◽  
Nod Genes ◽  
Nodule Initiation ◽  
Fix Genes ◽  
Nitrogen Fixation Genes

Genes that specify nodulation (nod genes) are only active in the free-living rhizobia or in the nodule initiation state of rhizobia. As soon as the repression of nod genes occurs in the bacteroids of the nodule, nifA is induced, while ntrC is inactivated and thus the nifA-mediated nif/fix genes are turned on. Limitation of available oxygen brings about the induction of nifA, which reflects the actual status of nif/fix gene activities in symbiotic state of rhizobia. Oxygen thus appears to be a major symbiotic signal to the expression of bacteroid nif/fix genes. Mutation of nifA or shortage of nifA product in wild-type rhizobia caused by the inhibition of multicopy nifH/fixA promoters leads to an abnormal development of nodules and premature degradation of bacteroids in nodules.Key words: nitrogen fixation, nodulation, nif/fix regulation, nifA mutant.

scholarly journals Transferrin-Conjugated SNALPs Encapsulating 2′-O-Methylated miR-34a for the Treatment of Multiple Myeloma

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Immacolata Scognamiglio ◽  
Maria Teresa Di Martino ◽  
Virginia Campani ◽  
Antonella Virgilio ◽  
Aldo Galeone ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Zeta Potential ◽  
Lipid Vesicles ◽  
Significant Inhibition ◽  
The Other ◽  
Transferrin Receptors ◽  
Proof Of Concept ◽  
Wild Type ◽  
Chemical Conjugation ◽  
Mean Size

Stable nucleic acid lipid vesicles (SNALPs) encapsulating miR-34a to treat multiple myeloma (MM) were developed. Wild type or completely 2′-O-methylated (OMet) MiR-34a was used in this study. Moreover, SNALPs were conjugated with transferrin (Tf) in order to target MM cells overexpressing transferrin receptors (TfRs). The type of miR-34a chemical backbone did not significantly affect the characteristics of SNALPs in terms of mean size, polydispersity index, and zeta potential, while the encapsulation of an OMet miR-34a resulted in a significant increase of miRNA encapsulation into the SNALPs. On the other hand, the chemical conjugation of SNALPs with Tf resulted in a significant decrease of the zeta potential, while size characteristics and miR-34a encapsulation into SNALPs were not significantly affected. In an experimental model of MM, all the animals treated with SNALPs encapsulating miR-34a showed a significant inhibition of the tumor growth. However, the use of SNALPs conjugated with Tf and encapsulating OMet miR-34a resulted in the highest increase of mice survival. These results may represent the proof of concept for the use of SNALPs encapsulating miR-34a for the treatment of MM.

Genetic characterization of Rhizobium sp. strain TAL1145 that nodulates tree legumes

1994 ◽  
Vol 40 (3) ◽  
pp. 208-215 ◽  
Author(s):  
M. L. C. George ◽  
J. P. W. Young ◽  
D. Borthakur
Keyword(s):  
Rhizobium Leguminosarum ◽  
Genetic Characterization ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Tree Legumes ◽  
Wide Range ◽  
The Common ◽  
Rrna Sequences ◽  
Rhizobium Sp

Rhizobium sp. strain TALI 145 nodulates Leucaena ieucocephaia and Phaseolus vulgaris, in addition to a wide range of tropical tree legumes. Six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. The common nod and nifA genes were situated approximately 17 kb apart, with the nodlJ genes in between. These clones enabled a derivative of TAL1145 carrying a partially deleted pSym to form ineffective nodules on both leucaena and bean, and a similar derivative of Rhizobium etli TAL182 to form ineffective nodules on bean. When two representative clones, pUHR9 and pUHR114, were each transferred to wild-type rhizobial strains, they allowed ineffective nodulation by Rhizobium meliloti on both leucaena and bean and by Rhizobium leguminosarum bv. viciae on bean. Transconjugants of R. leguminosarum bv. trifolii formed effective nodules on leucaena and ineffective nodules on bean. Tn5 mutagenesis of the symbiosis region resulted in a variety of nodulation and fixation phenotypes on leucaena and bean. On the basis of 16S rRNA sequences, TAL1145 was found to be distinct from both R. tropici and NGR234, the two groups of leucaena symbionts that were previously described.Key words: Rhizobium, Leucaena leucocephala, nodulation, nitrogen fixation.

scholarly journals Rv3131, a gene encoding nitroreductase, is essential for metronidazole activation in Mycobacterium tuberculosis under hypoxic condition

2020 ◽  
Author(s):  
Wenzhu Dong ◽  
Jin Shi ◽  
Ping Chu ◽  
Rongmei Liu ◽  
Shu’an Wen ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Anaerobic Bacteria ◽  
Aerobic Condition ◽  
Hypoxic Condition ◽  
Significant Inhibition ◽  
Wild Type ◽  
Minimal Inhibitory Concentrations ◽  
High Level ◽  
Nitroreductase Activity

Abstract ObjectivesThe impressive potency of metronidazole (MTZ) against anaerobic bacteria indicates the potential for killing anaerobic Mtb. However, how MTZ is activated in Mtb still remains unknown. We aimed to characterize the endogenous nitroreductase responsible for MTZ activation in anaerobic Mtb.MethodsThe minimal inhibitory concentrations (MICs) of Mtb isolates against MTZ were determined by microplate Alamar Blue assay. Intracellular anti-TB activities of MTZ and pyrazinamide (PZA) were tested in THP-1 cells infected by Mycobacterium tuberculosis (Mtb) H37Rv with a multiplicity of infection (MOI) of 10. The nitroreductase activity of purified wild-type Rv3131 and mutants were measured under anaerobic conditions generated by glucose oxidase/catalase system. Two-tailed unpaired Student’s t test was used to compare the difference between various groups.Results180 Mtb isolates (81.8%, 180/220) had MIC values higher than 16 μg/mL, and 40 had MIC values of 16 μg/mL, demonstrating high-level resistance to MTZ under aerobic condition. The number of viable bacteria in macrophages treated with MTZ was dramatically decreased by 71.3% after 5-day MTZ treatment, indicating significant inhibition of MTZ against anaerobic Mtb. In vitro biochemical analysis demonstrated that Rv3131 exhibited the NADPH oxidase activity under anaerobic condition. The substitutions of Cys75Ser and Cys279Ser could maintain 41.7% and 71.1% of enzyme activity compared to wild-type protein, respectively.ConclusionsOur data demonstrate that MTZ has more potent efficacy against intracellular Mtb than PZA. Rv3131 is identified as a nitroreductase enzyme in the activation of MTZ, and Cys75 of Rv3131 is the major active residue for nitroreductase activity.

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