scholarly journals RAR1, ROR1, and the Actin Cytoskeleton Contribute to Basal Resistance to Magnaporthe grisea in Barley

2005 ◽  
Vol 18 (5) ◽  
pp. 397-404 ◽  
Author(s):  
Birgit Jarosch ◽  
Nicholas C. Collins ◽  
Nina Zellerhoff ◽  
Ulrich Schaffrath
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Magnaporthe Grisea ◽  
Penetration Resistance ◽  
Blast Disease ◽  
Dependent Manner ◽  
Basal Resistance ◽  
Major Resistance Gene ◽  
Cytochalasin E ◽  
Dose Dependent

The fungus Magnaporthe grisea, the causal agent of rice blast disease, is a major pathogen of rice and is capable of producing epidemics on other cultivated cereals, including barley (Hordeum vulgare). We explored the requirements for basal resistance of barley against a compatible M. grisea isolate using both genetic and chemical approaches. Mutants of the RAR1 gene required for the function of major resistance gene-mediated resistance and mutants of the ROR1 and ROR2 genes required for full expression of cell-wall-penetration resistance against powdery mildew pathogens were examined for macroscopic and microscopic alterations in M. grisea growth and symptoms. RAR1 contributed to resistance in epidermis and mesophyll at different stages of fungal infection dependent on the MLO/mlo-5 status. Whereas no ROR2 effect was detected, ROR1 was found to contribute to cell-wall-penetration resistance, at least in the epidermis. Application of the actin agonist cytochalasin E promoted cell wall penetration by M. grisea in a dose-dependent manner, demonstrating an involvement of the actin cytoskeleton in penetration resistance.

scholarly journals Inhibition of Fungal Appressorium Formation by Pepper (Capsicum annuum) Esterase

2001 ◽  
Vol 14 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Young Soon Kim ◽  
Hyun Hwa Lee ◽  
Moon Kyung Ko ◽  
Chae Eun Song ◽  
Cheol-Yong Bae ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Capsicum Annuum ◽  
Magnaporthe Grisea ◽  
Dependent Manner ◽  
Appressorium Formation ◽  
Glutathione S Transferase ◽  
Porcine Liver ◽  
Esterase Gene ◽  
Dose Dependent ◽  
Dependent Signaling Pathway

A pepper esterase gene (PepEST) that is highly expressed during an incompatible interaction between pepper (Capsicum annuum) and the anthracnose fungus Colletotrichum gloeosporioides has been previously cloned. Glutathione-S-transferase-tagged recombinant PepEST protein expressed in Escherichia coli showed substrate specificity for p-nitrophenyl esters. Inoculation of compatible unripe pepper fruits with C. gloeosporioides spores amended with the recombinant protein did not cause anthracnose symptoms on the fruit. The recombinant protein has no fungicidal activity, but it significantly inhibits appressorium formation of the anthracnose fungus in a dose-dependent manner. An esterase from porcine liver also inhibited appressorium formation, and the recombinant protein inhibited appressorium formation in the rice blast fungus, Magnaporthe grisea. Inhibition of appressorium formation in M. grisea by the recombinant protein was reversible by treatment with cyclic AMP (cAMP) or 1,16-hexadecanediol. The results suggest that the recombinant protein regulates appressorium formation by modulating the cAMP-dependent signaling pathway in this fungus. Taken together, the PepEST esterase activity can inhibit appressorium formation of C. gloeosporioides, which may result in protection of the unripe fruit against the fungus.

scholarly journals Fungal auxin is a quorum-based modulator of blast disease severity

2021 ◽  
Author(s):  
Lihong Dong ◽  
Qing Shen ◽  
Cheng-Yen Chen ◽  
Lizheng Shen ◽  
Fan Yang ◽  
...  
Keyword(s):  
Rice Blast ◽  
Biological Function ◽  
Pyruvate Decarboxylase ◽  
Microbial Pathogens ◽  
Blast Disease ◽  
Dependent Manner ◽  
Acid Biosynthesis ◽  
Chemical Inhibition ◽  
Dose Dependent ◽  
Indole 3 Acetic Acid

Auxin is an important phytohormone regulating plant growth and development, and can also be produced by microbial pathogens including the rice-blast fungus Magnaporthe oryzae. However, the detailed biosynthesis pathway, biological function(s), and cellular distribution of such fungal auxin in M. oryzae remain largely unknown. Here, we report a sequential accumulation of intrinsic auxin in the three conidial cells, the infection structure (appressorium), and the invasive hyphae in M. oryzae. Such fungus-derived auxin was also secreted out and perceived by the host plants. A mitochondria-associated Indole-3-pyruvate decarboxylase, Ipd1, is essential for auxin/Indole-3-acetic acid biosynthesis in M. oryzae. The ipd1 mutant was defective in pathogenicity whereas overexpression of IPD1 led to enhanced virulence in rice. Chemical inhibition of fungal IAA biosynthesis, or its increase via external supplementation decreased or increased the severity of blast disease, respectively, in a dose-dependent manner. Furthermore, the IAA produced and secreted by M. oryzae governed the incidence and severity of blast disease in a quorum-dependent manner. Appressorium formation, conidial cell death critical for appressorium function, and the transcription of infection-related genes, MPG1 and INV1, directly correlated with cell density and/or IAA levels within the conidial population at the early stages of pathogenic development. Overall, our study revealed that the severity of blast disease is regulated via quorum sensing with intrinsic IAA serving as an associated signal transducer in rice blast.

Sub-membranous actin rings in the axon initial segment are resistant to the action of latrunculin

2019 ◽  
Vol 400 (9) ◽  
pp. 1141-1146 ◽  
Author(s):  
Amr Abouelezz ◽  
David Micinski ◽  
Aino Lipponen ◽  
Pirta Hotulainen
Keyword(s):  
Actin Cytoskeleton ◽  
Initial Segment ◽  
Axon Initial Segment ◽  
Dependent Manner ◽  
Latrunculin A ◽  
Actin Rings ◽  
Dose Dependent

Abstract The axon initial segment (AIS) comprises a sub-membranous lattice containing periodic actin rings. The overall AIS structure is insensitive to actin-disrupting drugs, but the effects of actin-disrupting drugs on actin rings lack consensus. We examined the effect of latrunculin A and B on the actin cytoskeleton of neurons in culture and actin rings in the AIS. Both latrunculin A and B markedly reduced the overall amount of F-actin in treated neurons in a dose-dependent manner, but the periodicity of actin rings remained unaffected. The insensitivity of AIS actin rings to latrunculin suggests they are relatively stable.

An investigation into plasmolysis in the oomycete Achlya bisexualis reveals that membrane–wall attachment points are sensitive to peptides containing the sequence RGD and that cell wall deposition can occur despite retraction of the protoplast

2012 ◽  
Vol 58 (10) ◽  
pp. 1212-1220 ◽  
Author(s):  
Kenny Chitcholtan ◽  
Elisa Harris ◽  
YuPing Yu ◽  
Chad Harland ◽  
Ashley Garrill
Keyword(s):  
Cell Wall ◽  
Focal Adhesions ◽  
Structure And Function ◽  
Dependent Manner ◽  
Wall Deposition ◽  
Attachment Sites ◽  
And Function ◽  
Dose Dependent ◽  
Cell Wall Deposition ◽  
Achlya Bisexualis

The structure and function of membrane–wall attachment sites in walled cells, and how these relate to animal focal adhesions, is an area that is poorly understood. In view of this, we investigated how membrane–wall attachments that form upon plasmolysis, respond to peptides that disrupt animal focal adhesions. The degree of cytoplasmic disruption during plasmolysis was also investigated. Upon hyperosmotic challenge, the protoplast in hyphae of the oomycete Achlya bisexualis typically retracted incompletely due to membrane–wall attachments. The inclusion, in the plasmolysing solution, of peptides containing the sequence RGD disrupted these attachments in a dose-dependent manner. In some hyphae, protoplast retraction stopped temporarily at attachment points — upon resumption of retraction, material was left that traced the outline of the static protoplast. Staining of this material with fluorescence brightener indicated the presence of cellulose, which suggests that wall deposition was able to occur despite plasmolysis. The F-actin cytoskeleton was disrupted during plasmolysis; peripheral F-actin staining was observed, but there was no distinct F-actin cap; staining was more diffuse; and there were fewer plaques compared with nonplasmolysed hyphae. Our data indicate that membrane–wall attachment points are sensitive to RGD-containing peptides and that wall deposition continues despite protoplast retraction and F-actin disruption.

scholarly journals Unveiling the Properties of Thai Stingless Bee Propolis via Diminishing Cell Wall-Associated Cryptococcal Melanin and Enhancing the Fungicidal Activity of Macrophages

Antibiotics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 420
Author(s):  
Ketsaya Mamoon ◽  
Patcharin Thammasit ◽  
Anupon Iadnut ◽  
Kuntida Kitidee ◽  
Usanee Anukool ◽  
...  
Keyword(s):  
Cell Wall ◽  
Complex Structure ◽  
Ethanolic Extract ◽  
Stingless Bee ◽  
Immunomodulatory Activity ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Yeast Infection ◽  
Chitin And Chitosan ◽  
Dose Dependent

Cryptococcus neoformans, a life-threatening human yeast pathogen, has the ability to produce melanin, which is one of the common virulence factors contributing to cryptococcal pathogenesis. This virulence factor is closely associated with the cryptococcal cell wall, specifically chitin and chitosan polysaccharides, a complex structure that is essential for maintaining cellular structure and integrity. In this study, we aim to investigate the effects of two stingless bee (SLB) propolis from Tetragonula laeviceps and Tetrigona melanoleuca against cell wall-associated melanin in C. neoformans, and its immune response in RAW 264.7 macrophage. The ethanolic extract of SLB propolis (EEP) has strongly exhibited anti-cryptococcal activity. Moreover, EEP from both sources reduced chitin/chitosan and melanin production against C. neoformans in a dose-dependent manner. Likewise, the mRNA expression level of CDA1, IPC1-PKC1 and LAC1 genes involved in the cryptococcal melanization pathway was significantly decreased at 2 mg/mL in EEP treatment. Additionally, pretreatment with EEP prior to yeast infection dramatically reduced intracellular replication of C. neoformans in RAW 264.7 macrophages in a dose-dependent manner. This study might be a new insight to use a natural powerful source, not only acting to target cell wall-associated molecules, but also being capable to explore a novel strategy by which dysregulation of these molecules leads to promote immunomodulatory activity.

scholarly journals Identification of a Fibronectin Binding Protein from Streptococcus mutans

2000 ◽  
Vol 68 (4) ◽  
pp. 1864-1870 ◽  
Author(s):  
Jean-San Chia ◽  
Chiou-Yueh Yeh ◽  
Jen-Yang Chen
Keyword(s):  
Endothelial Cells ◽  
Cell Wall ◽  
Molecular Mass ◽  
Streptococcus Mutans ◽  
Binding Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Affinity Column ◽  
Dependent Manner ◽  
Viridans Streptococci ◽  
Dose Dependent

ABSTRACT The interaction of viridans streptococci with components of the extracellular matrix (ECM) plays an important role in the pathogenesis of infective endocarditis. We have identified a surface protein ofStreptococcus mutans which binds the ECM constituent fibronectin (Fn). Initially, we found that S. mutans could adsorb soluble Fn in plasma, but with lower efficiency thanStreptococcus pyogenes. In addition, S. mutanscould bind immobilized Fn in a dose-dependent manner when tested using an enzyme-linked immunosorbent assay. Crude extracts of cell wall-associated proteins or extracellular proteins from S. mutans MT8148 specifically bound Fn through a protein with the molecular mass of ca. 130 kDa, as detected by far-Western immunoblotting. The candidate Fn binding protein (FBP-130) was purified to near homogeneity by using Fn coupled Sepharose 4B affinity column chromatography. A rabbit polyclonal antibody against FBP-130 reacted specifically with a protein of molecular mass of ca. 130 kDa in both cell wall and extracellular fractions, and the abundance of FBP was higher in the former than in the latter fractions. The purified FBP bound specifically to immobilized Fn, whereas the binding of soluble Fn to coated FBP could only be detected in the presence of high concentrations of Fn. The purified FBP, as well as anti-FBP immunoglobulin G, inhibited the adherence of S. mutans to immobilized Fn and endothelial cells (ECV304) in a dose-dependent manner. These results demonstrated that FBP-130 mediated the adherence of S. mutans specifically to Fn and endothelial cells in vitro. The characteristics of S. mutans and FBP-130 in binding Fn confirmed that viridans streptococci adopt different strategies in their interaction with ECM.

scholarly journals Description of a Novel Adhesin ofMycobacterium aviumSubsp.paratuberculosis

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Mariana Noelia Viale ◽  
Gabriela Echeverria-Valencia ◽  
Pablo Romasanta ◽  
María Laura Mon ◽  
Marisa Fernandez ◽  
...  
Keyword(s):  
Cell Wall ◽  
Epithelial Cells ◽  
Elongation Factor ◽  
Host Cells ◽  
Homology Search ◽  
2D Electrophoresis ◽  
Dependent Manner ◽  
A Cell ◽  
Immunogenic Proteins ◽  
Dose Dependent

The binding and ingestion ofMycobacterium aviumsubsp.paratuberculosis(MAP) by host cells are fibronectin (FN) dependent. In several species of mycobacteria, a specific family of proteins allows the attachment and internalization of these bacteria by epithelial cells through interaction with FN. Thus, the identification of adhesion molecules is essential to understand the pathogenesis of MAP. The aim of this study was to identify and characterize FN binding cell wall proteins of MAP. We searched for conserved adhesins within a large panel of surface immunogenic proteins of MAP and investigated a possible interaction with FN. For this purpose, a cell wall protein fraction was obtained and resolved by 2D electrophoresis. The immunoreactive spots were identified by MALDI-TOF MS and a homology search was performed. We selected elongation factor Tu (EF-Tu) as candidate for further studies. We demonstrated the FN-binding capability of EF-Tu using a ligand blot assay and also confirmed the interaction with FN in a dose-dependent manner by ELISA. The dissociation constant of EF-Tu was determined by surface plasmon resonance and displayed values within theμM range. These data support the hypothesis that this protein could be involved in the interaction of MAP with epithelial cells through FN binding.

scholarly journals New insights in to ancient resistance: the molecular side of cell wall appositions

2004 ◽  
Vol 85 (1) ◽  
pp. 49-52 ◽  
Author(s):  
David L. Greenshields ◽  
Guosheng Liu ◽  
Gopalan Selvaraj ◽  
Yangdou Wei
Keyword(s):  
Cell Wall ◽  
Cdna Library ◽  
Stress Responses ◽  
Redox Regulation ◽  
Global Analysis ◽  
Penetration Resistance ◽  
Post Inoculation ◽  
Powdery Mildew Fungus ◽  
Basal Resistance ◽  
Est Analysis

AbstractThe epidermis lies at the interface between a plant and its environment. As such, the epidermis is crucial for protecting the plant against environmental insults. We focus primarily on cell wall reinforcement-mediated penetration resistance (papilla-resistance) against fungal pathogen attack. The epidermal cell layer of cereal leaves is the only tissue interacting with the powdery mildew fungus,Blumeria graminis, and papilla formation at sites of fungal penetration attempts provides a basal resistance, hampering fungal invasion irrespective of host specific compatibility or incompatibility. To elucidate the genetic scaffolding of penetration resistance mechanisms, we constructed a cDNA library from wheat leaf epidermis at 24-48 h post inoculation withB. graminisf. sp.tritici. We have sequenced 3,000 expressed sequence tags (ESTs) from this cDNA library. EST analysis revealed a large proportion of genes involved in plant defense/stress responses (1/3) and a low frequency of “house-keeping” genes. Enrichment of defense genes from this EST collection has allowed us to identify several defense and signaling pathways that have been hitherto poorly characterized, including cell wall biosynthesis, vesicle trafficking, redox regulation and metal homeostasis. Our results suggest that a global analysis of transcripts from this epidermis-specific cDNA library makes it feasible to define a full set of genes involved in early plant resistance associated with cell wall modifications.

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