Characterization of a cell-surface antigen isolated from the plant pathogen Phytophthora parasitica var. nicotianae

1995 ◽  
Vol 73 (S1) ◽  
pp. 1104-1108 ◽  
Author(s):  
N. Séjalon ◽  
R. Dargent ◽  
F. Villalba ◽  
A. Bottin ◽  
M. Rickauer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Synthetic Medium ◽  
Immunogold Labelling ◽  
Phytophthora Parasitica ◽  
In Planta ◽  
Black Shank ◽  
A Cell ◽  
Defence Responses

The genus Phytophthora contains several species that are pathogenic to plants. Phytophthora parasitica var. nicotianae is the causal agent of the black shank disease of tobacco. From this fungus we have isolated and purified to homogeneity a 34-kDa glycoprotein (GP34) that elicits defence responses in tobacco. Among other features, this glycoprotein contains the rare amino acid hydroxyproline. Antibodies against GP34 permitted us to study its localization in vitro and in planta. Ultrastructural cytochemistry using immunogold labelling shows that GP34 is present in the cell wall into which it is secreted by vesicles when the fungus is grown on synthetic medium. In zoospores, labelling precedes and is strictly associated with the formation of a new cell wall. At early stages of infection of tobacco, only a faint labelling of the mycelium is observed. Later on it is enhanced in the incompatible interaction between the fungus and a resistant host cultivar. Key words: cell wall, elicitor, hydroxyproline, Phytophthora, tobacco.

scholarly journals Elicitin Genes Expressed In Vitro by Certain Tobacco Isolates of Phytophthora parasitica Are Down Regulated During Compatible Interactions

2001 ◽  
Vol 14 (3) ◽  
pp. 326-335 ◽  
Author(s):  
Virginie Colas ◽  
Sandrine Conrod ◽  
Paul Venard ◽  
Harald Keller ◽  
Pierre Ricci ◽  
...  
Keyword(s):  
Hypersensitive Response ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Compatible Interaction ◽  
Phytophthora Parasitica ◽  
In Planta ◽  
Black Shank ◽  
Phytophthora Spp ◽  
Compatible Interactions

Phytophthora spp. secrete proteins called elicitins in vitro that can specifically induce hypersensitive response and systemic acquired resistance in tobacco. In Phytophthora parasitica, the causal agent of black shank, most isolates virulent on tobacco are unable to produce elicitins in vitro. Recently, however, a few elicitin-producing P. parasitica strains virulent on tobacco have been isolated. We investigated the potential diversity of elicitin genes in P. parasitica isolates belonging to different genotypes and with various virulence levels toward tobacco as well as elicitin expression pattern in vitro and in planta. Although elicitins are encoded by a multigene family, parA1 is the main elicitin gene expressed. This gene is highly conserved among isolates, regardless of the elicitin production and virulence levels toward tobacco. Moreover, we show that elicitin-producing P. parasitica isolates virulent on tobacco down regulate parA1 expression during compatible interactions, whichever host plant is tested. Conversely, one elicitin-producing P. parasitica isolate that is pathogenic on tomato and avirulent on tobacco still expresses parA1 in the compatible interaction. Therefore, some P. parasitica isolates may evade tobacco recognition by down regulating parA1 in planta. The in planta down regulation of parA1 may constitute a suitable mechanism for P. parasitica to infect tobacco without deleterious consequences for the pathogen.

scholarly journals Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

2021 ◽  
Author(s):  
Mara Quaglia ◽  
Marika Bocchini ◽  
Benedetta Orfei ◽  
Roberto D’Amato ◽  
Franco Famiani ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Zinc Phosphate ◽  
Plant Defence ◽  
In Planta ◽  
Tomato Plants ◽  
Pathogenesis Related Protein ◽  
Defence Responses ◽  
Plant Defence Responses

AbstractThe purpose of this study was to determine whether zinc phosphate treatments of tomato plants (Solanum lycopersicum L.) can attenuate bacterial speck disease severity through reduction of Pseudomonas syringae pv. tomato (Pst) growth in planta and induce morphological and biochemical plant defence responses. Tomato plants were treated with 10 ppm (25.90 µM) zinc phosphate and then spray inoculated with strain DAPP-PG 215, race 0 of Pst. Disease symptoms were recorded as chlorosis and/or necrosis per leaf (%) and as numbers of necrotic spots. Soil treatments with zinc phosphate protected susceptible tomato plants against Pst, with reductions in both disease severity and pathogen growth in planta. The reduction of Pst growth in planta combined with significantly higher zinc levels in zinc-phosphate-treated plants indicated direct antimicrobial toxicity of this microelement, as also confirmed by in vitro assays. Morphological (i.e. callose apposition) and biochemical (i.e., expression of salicylic-acid-dependent pathogenesis-related protein PR1b1 gene) defence responses were induced by the zinc phosphate treatment, as demonstrated by histochemical and qPCR analyses, respectively. In conclusion, soil treatments with zinc phosphate can protect tomato plants against Pst attacks through direct antimicrobial activity and induction of morphological and biochemical plant defence responses.

scholarly journals L-form bacteria, cell walls and the origins of life

Open Biology ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 120143 ◽  
Author(s):  
Jeff Errington
Keyword(s):  
Cell Wall ◽  
Cell Envelope ◽  
Evolutionary Development ◽  
Last Common Ancestor ◽  
Bacterial Cells ◽  
A Cell ◽  
Evolutionary Radiations ◽  
Key Steps ◽  
Bacterial Domain

The peptidoglycan wall is a defining feature of bacterial cells and was probably already present in their last common ancestor. L-forms are bacterial variants that lack a cell wall and divide by a variety of processes involving membrane blebbing, tubulation, vesiculation and fission. Their unusual mode of proliferation provides a model for primitive cells and is reminiscent of recently developed in vitro vesicle reproduction processes. Invention of the cell wall may have underpinned the explosion of bacterial life on the Earth. Later innovations in cell envelope structure, particularly the emergence of the outer membrane of Gram-negative bacteria, possibly in an early endospore former, seem to have spurned further major evolutionary radiations. Comparative studies of bacterial cell envelope structure may help to resolve the early key steps in evolutionary development of the bacterial domain of life.

Isolation and first characterization of a cell-wall-degrading agent of Chlorella

1979 ◽  
Vol 66 (10) ◽  
pp. 525-526 ◽  
Author(s):  
G. Touet ◽  
H. G. Aach
Keyword(s):  
Cell Wall ◽  
A Cell

Identification and preliminary characterization of cell-wall-anchored proteins of Staphylococcus epidermidis

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1453-1464 ◽  
Author(s):  
M. Gabriela Bowden ◽  
Wei Chen ◽  
Jenny Singvall ◽  
Yi Xu ◽  
Sharon J. Peacock ◽  
...  
Keyword(s):  
Cell Wall ◽  
Staphylococcus Epidermidis ◽  
Tertiary Structure ◽  
Genomic Sequence ◽  
Human Infection ◽  
Pcr Analysis ◽  
Genes Encoding ◽  
Antibody Titres

Staphylococcus epidermidis is a ubiquitous human skin commensal that has emerged as a major cause of foreign-body infections. Eleven genes encoding putative cell-wall-anchored proteins were identified by computer analysis of the publicly available S. epidermidis unfinished genomic sequence. Four genes encode previously described proteins (Aap, Bhp, SdrF and SdrG), while the remaining seven have not been characterized. Analysis of primary sequences of the Staphylococcus epidermidis surface (Ses) proteins indicates that they have a structural organization similar to the previously described cell-wall-anchored proteins from S. aureus and other Gram-positive cocci. However, not all of the Ses proteins are direct homologues of the S. aureus proteins. Secondary and tertiary structure predictions suggest that most of the Ses proteins are composed of several contiguous subdomains, and that the majority of these predicted subdomains are folded into β-rich structures. PCR analysis indicates that certain genes may be found more frequently in disease isolates compared to strains isolated from healthy skin. Patients recovering from S. epidermidis infections had higher antibody titres against some Ses proteins, implying that these proteins are expressed during human infection. Western blot analyses of early-logarithmic and late-stationary in vitro cultures suggest that different regulatory mechanisms control the expression of the Ses proteins.

A somatic cell-derived system for studying both early and late mitotic events in vitro

1989 ◽  
Vol 94 (3) ◽  
pp. 449-462
Author(s):  
J. Nakagawa ◽  
G.T. Kitten ◽  
E.A. Nigg
Keyword(s):  
Chromatin Condensation ◽  
Nuclear Lamina ◽  
Free System ◽  
Cell Free System ◽  
Protein Substrates ◽  
Nuclear Envelope Breakdown ◽  
Biochemical Fractionation ◽  
A Cell

We describe a cell-free system for studying mitotic reorganization of nuclear structure. The system utilizes soluble extracts prepared from metaphase-arrested somatic chicken cells and supports both the disassembly and subsequent partial reassembly of exogenous nuclei. By fluorescence microscopy, biochemical fractionation, protein phosphorylation assays and electron microscopy, we show that chicken embryonic nuclei incubated in extracts prepared from metaphase-arrested chicken hepatoma cells undergo nuclear envelope breakdown, lamina depolymerization and chromatin condensation. These prophase-like events are strictly dependent on ATP and do not occur when nuclei are incubated in interphase extracts. Compared to interphase extracts, metaphase extracts show increased kinase activities toward a number of nuclear protein substrates, including lamins and histone H1; moreover, they specifically contain four soluble phosphoproteins of Mr 38,000, 75,000, 95,000 and 165,000. Following disassembly of exogenous nuclei in metaphase extracts, telophase-like reassembly of a nuclear lamina and re-formation of nuclear membranes around condensed chromatin can be induced by depletion of ATP from the extract. We anticipate that this reversible cell-free system will contribute to the identification and characterization of factors involved in regulatory and mechanistic aspects of mitosis.

scholarly journals Direct evidence for a new mode of plant defense against insects via a novel polygalacturonase-inhibiting protein expression strategy

2020 ◽  
Vol 295 (33) ◽  
pp. 11833-11844
Author(s):  
Wiebke Haeger ◽  
Jana Henning ◽  
David G. Heckel ◽  
Yannick Pauchet ◽  
Roy Kirsch
Keyword(s):  
Cell Wall ◽  
Plant Defense ◽  
Plant Cell Wall ◽  
Direct Evidence ◽  
Larval Growth ◽  
Gene Families ◽  
Preliminary Evidence ◽  
Cell Wall Polysaccharide ◽  
In Planta

Plant cell wall–associated polygalacturonase-inhibiting proteins (PGIPs) are widely distributed in the plant kingdom. They play a crucial role in plant defense against phytopathogens by inhibiting microbial polygalacturonases (PGs). PGs hydrolyze the cell wall polysaccharide pectin and are among the first enzymes to be secreted during plant infection. Recent studies demonstrated that herbivorous insects express their own PG multi-gene families, raising the question whether PGIPs also inhibit insect PGs and protect plants from herbivores. Preliminary evidence suggested that PGIPs may negatively influence larval growth of the leaf beetle Phaedon cochleariae (Coleoptera: Chrysomelidae) and identified BrPGIP3 from Chinese cabbage (Brassica rapa ssp. pekinensis) as a candidate. PGIPs are predominantly studied in planta because their heterologous expression in microbial systems is problematic and instability and aggregation of recombinant PGIPs has complicated in vitro inhibition assays. To minimize aggregate formation, we heterologously expressed BrPGIP3 fused to a glycosylphosphatidylinositol (GPI) membrane anchor, immobilizing it on the extracellular surface of insect cells. We demonstrated that BrPGIP3_GPI inhibited several P. cochleariae PGs in vitro, providing the first direct evidence of an interaction between a plant PGIP and an animal PG. Thus, plant PGIPs not only confer resistance against phytopathogens, but may also aid in defense against herbivorous beetles.

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