Key Molecules Involved in Beneficial Infection Process in Rhizobia–Legume Symbiosis

2010 ◽  
pp. 55-80 ◽  
Author(s):  
Alvaro Peix ◽  
Encarna Velázquez ◽  
Luis R. Silva ◽  
Pedro F. Mateos
Keyword(s):  
Infection Process ◽  
Legume Symbiosis

scholarly journals Aeschynomene evenia, a Model Plant for Studying the Molecular Genetics of the Nod-Independent Rhizobium-Legume Symbiosis

2012 ◽  
Vol 25 (7) ◽  
pp. 851-861 ◽  
Author(s):  
Jean-François Arrighi ◽  
Fabienne Cartieaux ◽  
Spencer C. Brown ◽  
Marguerite Rodier-Goud ◽  
Marc Boursot ◽  
...  
Keyword(s):  
Lotus Japonicus ◽  
Infection Process ◽  
Ancestral State ◽  
Model Legume ◽  
Hybridization Procedure ◽  
Bradyrhizobium Sp ◽  
Thread Formation ◽  
Legume Symbiosis ◽  
Independent Process ◽  
Set Up

Research on the nitrogen-fixing symbiosis has been focused, thus far, on two model legumes, Medicago truncatula and Lotus japonicus, which use a sophisticated infection process involving infection thread formation. However, in 25% of the legumes, the bacterial entry occurs more simply in an intercellular fashion. Among them, some Aeschynomene spp. are nodulated by photosynthetic Bradyrhizobium spp. that do not produce Nod factors. This interaction is believed to represent a living testimony of the ancestral state of the rhizobium–legume symbiosis. To decipher the mechanisms of this Nod-independent process, we propose Aeschynomene evenia as a model legume because it presents all the characteristics required for genetic and molecular analysis. It is a short-perennial and autogamous species, with a diploid and relatively small genome (2n = 20; 460 Mb/1C). A. evenia ‘IRFL6945’ is nodulated by the well-characterized photosynthetic Bradyrhizobium sp. strain ORS278 and is efficiently transformed by Agrobacterium rhizogenes. Aeschynomene evenia is genetically homozygous but polymorphic accessions were found. A manual hybridization procedure has been set up, allowing directed crosses. Therefore, it should be relatively straightforward to unravel the molecular determinants of the Nod-independent process in A. evenia. This should shed new light on the evolution of rhizobium–legume symbiosis and could have important agronomic implications.

scholarly journals MsPG3, aMedicago sativapolygalacturonase gene expressed during the alfalfa–Rhizobium melilotiinteraction

1998 ◽  
Vol 95 (16) ◽  
pp. 9687-9692 ◽  
Author(s):  
Jose A. Muñoz ◽  
Carmen Coronado ◽  
Javier Pérez-Hormaeche ◽  
Adam Kondorosi ◽  
Pascal Ratet ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Single Gene ◽  
Infection Process ◽  
Reverse Transcription Pcr ◽  
Thread Formation ◽  
Legume Symbiosis ◽  
Plant Cell Wall Degradation ◽  
Transgenic Root Nodules

Polygalacturonase (PG) is one of the most important enzymes associated with plant cell wall degradation. It has been proposed to participate in the early steps of theRhizobium–legume interaction. We have identified two classes of cDNA fragments corresponding to two classes of PG genes in theMedicagogenome. One of this class, represented by E2inM. truncatulaand Pl1inM. sativa, seems to be related to previously characterized plant PG genes expressed in pollen. We have isolated the genomic clone containing the entire gene corresponding to the second class (E3). We showed thatMsPG3is a single gene in theMedicagogenome coding for PG. By reverse transcription-PCR,MsPG3expression was detected in roots 1 day afterRhizobiuminoculation. The early induction of theMsPG3, as also seen byin situhybridization experiments, supports its involvement in the early stages of theRhizobium-legume infection process. In addition, by analyzing the expression of aMsPG3promoter-gusconstruct inVicia hirsuta-transgenic root nodules, we showed thatMsPG3was expressed in all cells of nodule primordia and in the cells of the invasion zone. By Northern blot,MsPG3transcripts are not detected in variousMedicagotissues, indicating that the function of this gene is related closely to symbiosis. Thus, our results strongly suggest the involvement ofMsPG3gene during meristem formation and/or in the infection process, probably by facilitating cell wall rearrangement, penetration of the bacteria through the root hair wall, or infection thread formation and release of bacteria in plant cells.MsPG3represents a class of PG genes, distinct from the pollen-specific genes, and it is the first pectic encoded enzyme demonstrated to be involved inRhizobium-legume symbiosis.

scholarly journals Essential Role for the BacA Protein in the Uptake of a Truncated Eukaryotic Peptide in Sinorhizobium meliloti

2008 ◽  
Vol 191 (5) ◽  
pp. 1519-1527 ◽  
Author(s):  
Victoria L. Marlow ◽  
Andreas F. Haag ◽  
Hajime Kobayashi ◽  
Vivien Fletcher ◽  
Marco Scocchi ◽  
...  
Keyword(s):  
Chronic Infection ◽  
Sinorhizobium Meliloti ◽  
Essential Role ◽  
Lipid A ◽  
Membrane Lipid ◽  
Infection Process ◽  
Legume Symbiosis ◽  
Intracellular Infections ◽  
Peptide Uptake

ABSTRACT The inner membrane BacA protein is essential for the establishment of chronic intracellular infections by Sinorhizobium meliloti and Brucella abortus within plant and mammalian hosts, respectively. In their free-living state, S. meliloti and B. abortus mutants lacking BacA have reductions in their outer membrane lipid A very-long-chain fatty acid (VLCFA) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. In this paper we investigate the hypothesis that BacA is involved in peptide uptake in S. meliloti. We determined that an S. meliloti ΔbacA mutant is completely resistant to a truncated form of the eukaryotic peptide Bac7, Bac7(1-16), and this phenotype appears to be independent of its lipid A alteration. Subsequently, we discovered that BacA and/or Escherichia coli SbmA is essential for fluorescently labeled Bac7(1-16) uptake in S. meliloti. Given that there are hundreds of root nodule-specific peptides within the legume host, our data suggest that BacA-mediated peptide uptake could play a central role in the chronic infection process of S. meliloti. However, since we determined that two symbiotically defective S. meliloti bacA site-directed mutants (with the Q193G and R389G mutations, respectively) with known reductions in their lipid A VLCFA contents are still capable of peptide uptake, these findings suggest that BacA-dependent peptide uptake cannot fully account for the essential role of BacA in the legume symbiosis. Further, they provide evidence that the BacA function that leads to the S. meliloti lipid A VLCFA modification plays a key role in the chronic infection of legumes.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

Infection process of wheat streak mosaic virus in clinostated Apogee wheat plants

2003 ◽  
Vol 8 (5-6) ◽  
pp. 211-215 ◽  
Author(s):  
L.T. Mischenko ◽  
◽  
T. Kiihne ◽  
I.A. Mischenko ◽  
A.L. Boyko ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Wheat Streak Mosaic Virus ◽  
Infection Process

POSSIBILITIES OF BIOLOGICAL AND MATHEMATICAL MODELING OF THE INFECTION CAUSED BY EPSTEIN–BARR VIRUS

2020 ◽  
Vol 99 (6) ◽  
pp. 226-231
Author(s):  
A.V. Permyakova ◽  
◽  
A.V. Sazhin ◽  
E.V. Melekhina ◽  
A.V. Gorelov ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Immune Regulation ◽  
Epstein Barr Virus ◽  
Virus Isolation ◽  
Biological Fluids ◽  
Infection Process ◽  
Host Organism ◽  
Barr Virus ◽  
Virus Excretion ◽  
Epstein Barr

The review presents the existing biological and mathematical models of the infection process caused by the Epstein–Barr virus. The existence of the Epstein–Barr virus in the host organism can be described by a model representing a cycle of six consecutive stages, each of them has its own independent variant of immune regulation. The phenomenon of virus excretion in biological fluids, in particular, in saliva, is modeled using differential equations. Usage of mathematical modeling allows us to supplement existing knowledge about the pathogenesis of the infectious process caused by the Epstein–Barr virus, as well as to determine threshold levels of virus isolation in non-sterile environments for the diagnosis of active forms of infection.

The Carbohydrate‐Nitrogen Relation in Legume Symbiosis 1

1939 ◽  
Vol 31 (6) ◽  
pp. 497-502 ◽  
Author(s):  
P. W. Wilson ◽  
E. B. Fred
Keyword(s):  
Legume Symbiosis

scholarly journals Effects of heterogeneity in infection-exposure history and immunity on the dynamics of a protozoan parasite

2007 ◽  
Vol 4 (16) ◽  
pp. 841-849 ◽  
Author(s):  
Maite Severins ◽  
Don Klinkenberg ◽  
Hans Heesterbeek
Keyword(s):  
Dynamic Behaviour ◽  
Protozoan Parasite ◽  
Host Population ◽  
Infection Process ◽  
Control Measures ◽  
Complex Dynamic ◽  
Systems Models ◽  
Exposure History ◽  
The Relationship ◽  
Initial Contamination

Infection systems where traits of the host, such as acquired immunity, interact with the infection process can show complex dynamic behaviour with counter-intuitive results. In this study, we consider the traits ‘immune status’ and ‘exposure history’, and our aim is to assess the influence of acquired individual heterogeneity in these traits. We have built an individual-based model of Eimeria acervulina infections, a protozoan parasite with an environmental stage that causes coccidiosis in chickens. With the model, we simulate outbreaks of the disease under varying initial contaminations. Heterogeneity in the traits arises stochastically through differences in the dose and frequency of parasites that individuals pick up from the environment. We find that the relationship between the initial contamination and the severity of an outbreak has a non-monotonous ‘wave-like’ pattern. This pattern can be explained by an increased heterogeneity in the host population caused by the infection process at the most severe outbreaks. We conclude that when dealing with these types of infection systems, models that are used to develop or evaluate control measures cannot neglect acquired heterogeneity in the host population traits that interact with the infection process.

scholarly journals Biofilm Formation in Xanthomonas arboricola pv. pruni: Structure and Development

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 546
Author(s):  
Pilar Sabuquillo ◽  
Jaime Cubero
Keyword(s):  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Environmental Changes ◽  
Nutrient Content ◽  
Infection Process ◽  
Bacterial Attachment ◽  
Key Factors ◽  
Cell Structures ◽  
Microscopy Techniques

Xanthomonasarboricola pv. pruni (Xap) causes bacterial spot of stone fruit and almond, an important plant disease with a high economic impact. Biofilm formation is one of the mechanisms that microbial communities use to adapt to environmental changes and to survive and colonize plants. Herein, biofilm formation by Xap was analyzed on abiotic and biotic surfaces using different microscopy techniques which allowed characterization of the different biofilm stages compared to the planktonic condition. All Xap strains assayed were able to form real biofilms creating organized structures comprised by viable cells. Xap in biofilms differentiated from free-living bacteria forming complex matrix-encased multicellular structures which become surrounded by a network of extracellular polymeric substances (EPS). Moreover, nutrient content of the environment and bacterial growth have been shown as key factors for biofilm formation and its development. Besides, this is the first work where different cell structures involved in bacterial attachment and aggregation have been identified during Xap biofilm progression. Our findings provide insights regarding different aspects of the biofilm formation of Xap which improve our understanding of the bacterial infection process occurred in Prunus spp and that may help in future disease control approaches.

scholarly journals The YadA Protein of Yersinia pseudotuberculosis Mediates High-Efficiency Uptake into Human Cells under Environmental Conditions in Which Invasin Is Repressed

2002 ◽  
Vol 70 (9) ◽  
pp. 4880-4891 ◽  
Author(s):  
Julia Eitel ◽  
Petra Dersch
Keyword(s):  
Extracellular Matrix ◽  
Mammalian Cells ◽  
Yersinia Pseudotuberculosis ◽  
High Efficiency ◽  
Environmental Parameters ◽  
Infection Process ◽  
Nutrient Concentrations ◽  
Integrin Receptors ◽  
Uptake Process ◽  
High Level

ABSTRACT The YadA protein is a major adhesin of Yersinia pseudotuberculosis that promotes tight adhesion to mammalian cells by binding to extracellular matrix proteins. In this study, we first addressed the possibility of competitive interference of YadA and the major invasive factor invasin and found that expression of YadA in the presence of invasin affected neither the export nor the function of invasin in the outer membrane. Furthermore, expression of YadA promoted both bacterial adhesion and high-efficiency invasion entirely independently of invasin. Antibodies against fibronectin and β1 integrins blocked invasion, indicating that invasion occurs via extracellular-matrix-dependent bridging between YadA and the host cell β1 integrin receptors. Inhibitor studies also demonstrated that tyrosine and Ser/Thr kinases, as well as phosphatidylinositol 3-kinase, are involved in the uptake process. Further expression studies revealed that yadA is regulated in response to several environmental parameters, including temperature, ion and nutrient concentrations, and the bacterial growth phase. In complex medium, YadA production was generally repressed but could be induced by addition of Mg2+. Maximal expression of yadA was obtained in exponential-phase cells grown in minimal medium at 37°C, conditions under which the invasin gene is repressed. These results suggest that YadA of Y. pseudotuberculosis constitutes another independent high-level uptake pathway that might complement other cell entry mechanisms (e.g., invasin) at certain sites or stages during the infection process.

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