Ultrastructural effects of thaxtomin A produced by Streptomyces scabies on mature potato tuber tissues

2000 ◽  
Vol 78 (3) ◽  
pp. 374-380 ◽  
Author(s):  
Claudia Goyer ◽  
Pierre-Mathieu Charest ◽  
Vicky Toussaint ◽  
Carole Beaulieu
Keyword(s):  
Cell Wall ◽  
Potato Tuber ◽  
Common Scab ◽  
Streptomyces Scabies ◽  
Intercellular Spaces ◽  
Electron Dense Material ◽  
Thaxtomin A ◽  
Fibrillar Material ◽  
Parenchyma Cells ◽  
Mature Field

The cytological and ultrastructural modifications induced by thaxtomin A, a phytotoxin produced by Streptomyces scabies, were analyzed on mature field-grown potato tuber tissues. In tissue sampled during the first 12 h after treatment with thaxtomin A, the plasmalemma of parenchyma cells was detached from the cell wall in several places. However, the plasmalemma did not appear ruptured. The intercellular spaces between the retracted plasmalemma and the cell wall often contained fibrillar material. After a longer period of time, cells from tissues treated with thaxtomin A showed significant disorganization, such as detachment and invagination of the plasmalemma, the presence of a fibrillar-like material in the cytoplasm, and electron-dense material associated with moribund cellular features.Key words: common scab, potato, phytotoxin, Solanum tuberosum.

Effect of amino acids on thaxtomin A biosynthesis by Streptomyces scabies

2002 ◽  
Vol 48 (4) ◽  
pp. 359-364 ◽  
Author(s):  
Annie Lauzier ◽  
Claudia Goyer ◽  
Luc Ruest ◽  
Ryszard Brzezinski ◽  
Don L Crawford ◽  
...  
Keyword(s):  
Amino Acids ◽  
Inhibitory Action ◽  
Common Scab ◽  
Aromatic Amino Acids ◽  
Inhibitory Effect ◽  
Nitroaromatic Compounds ◽  
Streptomyces Scabies ◽  
Regulatory Effect ◽  
Thaxtomin A ◽  
Metabolic Precursors

The regulatory effect of amino acids on the production of thaxtomin A, a phytotoxin produced by Streptomyces scabies, was investigated. Tryptophan had an important inhibitory effect on the toxin biosynthesis in all five strains of S. scabies tested. Two other aromatic amino acids (tyrosine and phenylalanine) also inhibited thaxtomin A biosynthesis, while aliphatic amino acids did not cause an important decline in thaxtomin A production. Methylation of tryptophan prevented or reduced the inhibitory effect on thaxtomin A biosynthesis. In spite of the inhibitory action of tryptophan and phenylalanine on thaxtomin A production, incorporation of these radiolabeled molecules into thaxtomin A confirmed that they are metabolic precursors for the biosynthesis of the phytotoxin.Key words: thaxtomin A, phytotoxin, Streptomyces scabies, common scab, nitroaromatic compounds, amino acids.

scholarly journals Draft Genome Sequence of the Plant Pathogen Streptomyces sp. Strain 11-1-2

2017 ◽  
Vol 5 (37) ◽  
Author(s):  
Luke Bown ◽  
Dawn R. D. Bignell
Keyword(s):  
Potato Tuber ◽  
Genome Sequence ◽  
Plant Pathogen ◽  
Common Scab ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Filamentous Bacterium ◽  
Highly Pathogenic ◽  
Streptomyces Sp ◽  
Thaxtomin A

ABSTRACT Streptomyces sp. strain 11-1-2 is a Gram-positive filamentous bacterium that was isolated from a common scab lesion on a potato tuber. The strain is highly pathogenic to plants but does not produce the virulence-associated Streptomyces phytotoxin thaxtomin A. Here, we report the draft genome sequence of Streptomyces sp. 11-1-2.

scholarly journals Characterizing Hyperspectral Microscope Imagery for Classification of Blueberry Firmness with Deep Learning Methods

Agronomy ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 85
Author(s):  
Bosoon Park ◽  
Tae-Sung Shin ◽  
Jeong-Seok Cho ◽  
Jeong-Ho Lim ◽  
Ki-Jae Park
Keyword(s):  
Cell Wall ◽  
Deep Learning ◽  
Cell Adhesion ◽  
Spectral Characteristics ◽  
Parenchyma Cell ◽  
Life Quality ◽  
Intercellular Spaces ◽  
Parenchyma Cells ◽  
Cell Shapes ◽  
Cell To Cell Adhesion

Firmness is an important quality indicator of blueberries. Firmness loss (or softening) of postharvest blueberries has posed a challenge in its shelf-life quality control and can be delineated with its microstructural changes. To investigate spatial and spectral characteristics of microstructures based on firmness, hyperspectral microscope imaging (HMI) was employed for this study. The mesocarp area with 20× magnification of blueberries was selectively imaged with a Fabry–Perot interferometer HMI system of 400–1000 nm wavelengths, resulting in 281 hypercubes of parenchyma cells in a resolution of 968 × 608 × 300 pixels. After properly processing each hypercube of parenchyma cells in a blueberry, the cell image with different firmness was examined based on parenchyma cell shape, cell wall segment, cell-to-cell adhesion, and size of intercellular spaces. Spectral cell characteristics of firmness were also sought based on the spectral profile of cell walls with different image preprocessing methods. The study found that softer blueberries (1.96–3.92 N) had more irregular cell shapes, lost cell-to-cell adhesion, loosened and round cell wall segments, large intercellular spaces, and cell wall colors that were more red than the firm blueberries (6.86–8.83 N). Even though berry-to-berry (or image-to-image) variations of the characteristics turned out large, the deep learning model with spatial and spectral features of blueberry cells demonstrated the potential for blueberry firmness classification with Matthew’s correlation coefficient of 73.4% and accuracy of 85% for test set.

scholarly journals Contribution of the β-glucosidase BglC to the Onset of the Pathogenic Lifestyle of Streptomyces scabies

2017 ◽  
Author(s):  
Samuel Jourdan ◽  
Isolde M. Francis ◽  
Benoit Deflandre ◽  
Elodie Tenconi ◽  
Jennifer Riley ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Common Scab ◽  
Streptomyces Scabies ◽  
Null Mutant ◽  
Enzymatic Assays ◽  
Thaxtomin A ◽  
Proposed Model ◽  
Synthase Inhibitor ◽  
Increased Activity

AbstractCommon scab disease on root and tuber plants is caused by Streptomyces scabies and related species which use the cellulose synthase inhibitor thaxtomin A as main phytotoxin. Thaxtomin production is primarily triggered by the import of cello-oligosaccharides. Once inside the cell, the fate of the cello-oligosaccharides is dichotomized into i) fueling glycolysis with glucose for the saprophytic lifestyle through the action of β-glucosidase(s) (BG), and ii) eliciting the pathogenic lifestyle by inhibiting the CebR-mediated transcriptional repression of thaxtomin biosynthetic genes. Here we investigated the role of scab57721 encoding a putative BG (BglC) in the onset of the pathogenicity of S. scabies. Enzymatic assays showed that BglC was able to release glucose from cellobiose, cellotriose and all other cello-oligosaccharides tested. Its inactivation resulted in a phenotype opposite to what was expected as we monitored reduced production of thaxtomin when the mutant was cultivated on media containing cello-oligosaccharides as unique carbon source. This unexpected phenotype could be attributed to the highly increased activity of alternative intracellular BGs, probably as a compensation of bglC inactivation, which then prevented cellobiose and cellotriose accumulation to reduce the activity of CebR. In contrast, when the bglC null mutant was cultivated on media devoid of cello-oligosaccharides it instead constitutively produced thaxtomin. This observed hypervirulent phenotype does not fit with the proposed model of the cello-oligosaccharide-mediated induction of thaxtomin production and suggests that the role of BglC in the route to the pathogenic lifestyle of S. scabies is more complex than currently presented.

Cell wall protuberances in the resin-pocket callus of Pinus nigra

1984 ◽  
Vol 62 (3) ◽  
pp. 570-574 ◽  
Author(s):  
L. A. Donaldson ◽  
A. P. Singh
Keyword(s):  
Cell Wall ◽  
Callus Tissue ◽  
Middle Lamella ◽  
Pinus Nigra ◽  
Primary Wall ◽  
Light Microscope Level ◽  
Fibrillar Material ◽  
Resin Pocket ◽  
Parenchyma Cells ◽  
Resin Pockets

Cell wall protuberances are found on the outer surface of parenchyma cells in callus tissue lining resin pockets in the wood of Pinus nigra Arn. The protuberances occur in a variety of forms ranging from bumps to distinctly stalked structures. They have a distinctive internal structure consisting of areas of fibrillar material of various densities and textures. The adjacent middle lamella often appears to be continuous with regions within the protuberance. No direct connection between the primary wall and the protuberance is observed, although staining at the light-microscope level indicates a similarity between areas of the protuberance and the primary wall. Protuberances are found only on parenchyma cells which have not developed secondary walls.

Ultrastructural effects of thaxtomin A produced by Streptomyces scabies on mature potato tuber tissues

2000 ◽  
Vol 78 (3) ◽  
pp. 374-380 ◽  
Author(s):  
Claudia Goyer ◽  
Pierre-Mathieu Charest ◽  
Vicky Toussaint ◽  
Carole Beaulieu
Keyword(s):  
Potato Tuber ◽  
Streptomyces Scabies ◽  
Thaxtomin A

Characterization of Streptomyces scabies mutants deficient in melanin biosynthesis

2004 ◽  
Vol 50 (9) ◽  
pp. 705-709 ◽  
Author(s):  
Julie Beauséjour ◽  
Carole Beaulieu
Keyword(s):  
Stress Resistance ◽  
Common Scab ◽  
Wild Strain ◽  
Streptomyces Scabies ◽  
Potato Tubers ◽  
Melanin Biosynthesis ◽  
Thaxtomin A ◽  
Pleiotrophic Effects ◽  
Higher Sensitivity

Streptomyces scabies, a causal agent of common scab, produces both melanin and a secondary metabolite called thaxtomin A. To establish a possible relation between melanin and thaxtomin A production in S. scabies, we carried out N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis and isolated 11 melanin-negative mutants of S. scabies EF-35. These mutants were characterized for thaxtomin A production, pathogenicity, sporulation, and stress resistance. Nine of these mutants showed a significant reduction in thaxtomin A production when compared with the wild strain. However, only a few mutants exhibited a reduced level of virulence or a loss in their ability to induce common scab symptoms on potato tubers. Other pleiotrophic effects, such as higher sensitivity to heavy metals and incapacity to sporulate under certain stress conditions, were also associated with a deficiency in melanin production.Key words: common scab, potato, secondary metabolism, stress, thaxtomin.

Production of thaxtomin A by Streptomyces scabies strains in plant extract containing media

1999 ◽  
Vol 45 (9) ◽  
pp. 764-768 ◽  
Author(s):  
Julie Beauséjour ◽  
Claudia Goyer ◽  
Joanne Vachon ◽  
Carole Beaulieu
Keyword(s):  
Minimal Medium ◽  
Biosynthetic Pathway ◽  
Common Scab ◽  
Culture Media ◽  
Streptomyces Scabies ◽  
Production Medium ◽  
Thaxtomin A ◽  
Oat Bran ◽  
Plant Polymer ◽  
Esterase Activities

Thaxtomin A production by Streptomyces scabies is induced by plant extracts in culture media. We compared the production of thaxtomin A by three Streptomyces scabies strains (EF-35, CG1, and ATCC 49173) in different culture media in a first attempt to identify the plant molecules required for the biosynthesis of thaxtomin A. Thaxtomin A production varied greatly among media and among S. scabies strains. Strain CG1 presented a higher production than the other strains in all complex media. Oat bran broth is the best thaxtomin A production medium, and suberin is the only plant polymer allowing the production of thaxtomin A in minimal medium. The three S. scabies strains had extracellular esterase activities when grown in the presence of potato suberin or oat bran. We suggest that extracellular esterases allow the release from lipid polymers of plant molecules that may act as inducers for thaxtomin A biosynthesis genes or as precursors in the biosynthetic pathway of thaxtomin A.Key words: common scab, phytotoxin, suberin, esterase.

scholarly journals Characterization of the Coronatine-Like Phytotoxins Produced by the Common Scab Pathogen Streptomyces scabies

2015 ◽  
Vol 28 (4) ◽  
pp. 443-454 ◽  
Author(s):  
Joanna K. Fyans ◽  
Mead S. Altowairish ◽  
Yuting Li ◽  
Dawn R. D. Bignell
Keyword(s):  
Amino Acid ◽  
Gene Cluster ◽  
Pseudomonas Syringae ◽  
Common Scab ◽  
Biosynthetic Gene Cluster ◽  
Major Product ◽  
Streptomyces Scabies ◽  
Coronafacic Acid ◽  
Thaxtomin A ◽  
Metabolites Production

Streptomyces scabies is an important causative agent of common scab disease of potato tubers and other root crops. The primary virulence factor produced by this pathogen is a phytotoxic secondary metabolite called thaxtomin A, which is essential for disease development. In addition, the genome of S. scabies harbors a virulence-associated biosynthetic gene cluster called the coronafacic acid (CFA)-like gene cluster, which was previously predicted to produce metabolites that resemble the Pseudomonas syringae coronatine (COR) phytotoxin. COR consists of CFA linked to an ethylcyclopropyl amino acid called coronamic acid, which is derived from L-allo-isoleucine. Using a combination of genetic and chemical analyses, we show that the S. scabies CFA-like gene cluster is responsible for producing CFA-L-isoleucine as the major product as well as other minor COR-like metabolites. Production of the metabolites was shown to require the cfl gene, which is located within the CFA-like gene cluster and encodes an enzyme involved in ligating CFA to its amino acid partner. CFA-L-isoleucine purified from S. scabies cultures was shown to exhibit bioactivity similar to that of COR, though it was found to be less toxic than COR. This is the first report demonstrating the production of coronafacoyl phytotoxins by S. scabies, which is the most prevalent scab-causing pathogen in North America.

Biotransformation of the Streptomyces scabies phytotoxin thaxtomin A by the fungus Aspergillus niger

2004 ◽  
Vol 50 (2) ◽  
pp. 121-126 ◽  
Author(s):  
George Lazarovits ◽  
Jackie Hill ◽  
Russell R King ◽  
Larry A Calhoun
Keyword(s):  
Aspergillus Niger ◽  
Common Scab ◽  
Streptomyces Scabies ◽  
Fungal Isolate ◽  
Growth Media ◽  
Optimum Conditions ◽  
Mass Spectral ◽  
Thaxtomin A ◽  
Toxic Metabolites ◽  
Incubation Periods

Of several hundred microorganisms randomly selected from the environment, only a fungal isolate identified as Aspergillus niger van Tiegham var. niger was found to transform the phytotoxin thaxtomin A to much less toxic metabolites. The rate and extent of transformation of thaxtomin A was tested under a variety of conditions, including different growth media, biomass concentrations, incubation periods, and shaker speeds. Under optimum conditions the fungus converted thaxtomin A into two major and five minor metabolites. The two major metabolites and three of the five minor metabolites were fully characterized by a combination of mass spectral and nuclear magnetic resonance techniques. When assayed on aseptically produced mini-tubers, the major metabolites proved to be much less phytotoxic than thaxtomin A.Key words: Aspergillus niger van Tiegham var. niger, biotransformation, common scab, phytotoxins, Streptomyces scabies, thaxtomin A.

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