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.

scholarly journals Characterization of a New Streptomyces Strain, DS3024, That Causes Potato Common Scab

Plant Disease ◽  
2009 ◽  
Vol 93 (12) ◽  
pp. 1329-1334 ◽  
Author(s):  
J. J. Hao ◽  
Q. X. Meng ◽  
J. F. Yin ◽  
W. W. Kirk
Keyword(s):  
Common Scab ◽  
Potato Tubers ◽  
North Central ◽  
Thaxtomin A ◽  
The North ◽  
Streptomyces Spp ◽  
Common Marker ◽  
Central United States ◽  
Potato Common Scab

A novel strain of Streptomyces (named DS3024) was isolated from a potato field in Michigan in 2006. The taxonomy of the organism was determined by morphology, biochemistry, and genetic analysis. Analysis of the 16S ribosomal RNA gene sequence indicated that the organism was most similar to an isolate of Streptomyces sp., ME02-6979.3a, which is not pathogenic to potato tubers but is distinct from other known pathogenic Streptomyces spp. Strain DS3024 has genes that encode thaxtomin synthetase (txtAB), which is required for pathogenicity and virulence, and tomatinase (tomA), which is a common marker for many pathogenic Streptomyces spp. However, the nec1 gene (associated with virulence in most pathogenic Streptomyces spp.) was not detected. The new strain was capable of growth at pH 4.5, caused necrosis on potato tuber slices, and produced thaxtomin A. In greenhouse experiments, DS3024 caused scab symptoms on potato tubers similar to those caused by Streptomyces scabies on tubers of potato cv. Atlantic, which is scab susceptible. We propose that DS3024 is a new strain of Streptomyces capable of causing common scab on potato tubers. The prevalence of this strain of Streptomyces in potato-producing areas in the north-central United States has not been determined.

scholarly journals Characterization of Streptomyces scabies isolates from potato tubers its pathogenic variations in Rawalpindi District

2014 ◽  
Vol 4 (1) ◽  
pp. 1-6
Author(s):  
S. Shazia ◽  
F. Naz ◽  
A. Rauf ◽  
M. Inam-ul-Haq ◽  
S. Bushra
Keyword(s):  
Solanum Tuberosum L ◽  
Economic Loss ◽  
Streptomyces Scabies ◽  
Potato Tubers ◽  
Yield And Quality ◽  
Isolation And Characterization ◽  
Pathogenic Variation ◽  
Important Disease

Potato (Solanum tuberosum L.) has various biotic constraints in its production due to pest attack. Among these, common scab caused by streptomyces scabies is an important disease in potato which causes economic loss with respect to plant yield and quality of tubers. The present study was conducted to determine the pathogenicity, pathogenic variation, characterization of morphological, physiological and biochemical aspects of Streptomyces associated with potato tubers grown in Rawalpindi district. Severity data and pathogenic variation of disease was studied by using different isolation and characterization techniques.

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 Isolation and Characterization of Plant-Pathogenic Streptomyces Species Associated with Common Scab-Infected Potato Tubers in Newfoundland

2016 ◽  
Vol 106 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Joanna K. Fyans ◽  
Luke Bown ◽  
Dawn R. D. Bignell
Keyword(s):  
Common Scab ◽  
Virulence Gene ◽  
Potato Scab ◽  
Potato Tubers ◽  
Streptomyces Species ◽  
Genus Streptomyces ◽  
Thaxtomin A ◽  
Streptomyces Spp ◽  
Putative Virulence Gene ◽  
Isolation And Characterization

Potato common scab (CS) is an economically important crop disease that is caused by several members of the genus Streptomyces. In this study, we characterized the plant-pathogenic Streptomyces spp. associated with CS-infected potato tubers harvested in Newfoundland, Canada. A total of 17 pathogenic Streptomyces isolates were recovered from potato scab lesions, of which eight were determined to be most similar to the known CS pathogen S. europaeiscabiei. All eight S. europaeiscabiei isolates were found to produce the thaxtomin A phytotoxin and to harbor the nec1 virulence gene, and most also carry the putative virulence gene tomA. The remaining isolates appear to be novel pathogenic species that do not produce thaxtomin A, and only two of these isolates were determined to harbor the nec1 or tomA genes. Of the non-thaxtomin-producing isolates, strain 11-1-2 was shown to exhibit a severe pathogenic phenotype against different plant hosts and to produce a novel, secreted phytotoxic substance. This is the first report documenting the plant-pathogenic Streptomyces spp. associated with CS disease in Newfoundland. Furthermore, our findings provide further evidence that phytotoxins other than thaxtomin A may also contribute to the development of CS by Streptomyces spp.

scholarly journals Investigation of Streptomyces scabies Causing Potato Scab by Various Detection Techniques, Its Pathogenicity and Determination of Host-Disease Resistance in Potato Germplasm

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 760
Author(s):  
Sohaib Ismail ◽  
Bo Jiang ◽  
Zohreh Nasimi ◽  
M. Inam-ul-Haq ◽  
Naoki Yamamoto ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Common Scab ◽  
Streptomyces Scabies ◽  
Potato Cultivars ◽  
Potato Tubers ◽  
Streptomyces Species ◽  
Detection Techniques ◽  
Streptomyces Spp ◽  
Geographical Regions

Streptomyces scabies is a Gram-positive bacterial pathogen that causes common scab disease to several crops, particularly in the potato. It is a soil borne pathogen, a very devastating scab pathogen and difficult to manage in the field. Streptomyces has several species that cause common scab such as S. scabiei, S. acidiscabies, S. europaeiscabiei, S. luridiscabiei, S. niveiscabiei, S. puniciscabiei, S. reticuliscabiei, S. stelliscabiei, S. turgidiscabies, S. ipomoeae. Common scab disease harmfully affects potato economic and market value due to the presence of black spots on the tuber. Owing to its genetic diversity and pathogenicity, the determination of pathogen presence in potato fields is still challenging. In this study, S. scabies genetic diversity was measured by surveying five potato-growing areas of Pakistan during the growing season 2019. A total of 50 Streptomyces isolates, including S. scabies, S. acidiscabies, S. griseoflavus were isolated and identified based on morphologic, biochemical and molecular analysis. Virulent confirmation assays confirmed ten virulent strains of Streptomyces spp. On the potato cultivars Cardinal and Santee. Among the Streptomyces species, S. scabies showed the highest scab index, followed by S. acidiscabies and S. griseoflavus by exhibiting the scab-like lesions on potato tubers. Ten potato cultivars were screened against these virulent isolates of Streptomyces. The Faisalabad white variety showed the highest scab index followed By Cardinal, Tourag, Kuroda, Santee, Lady Rosetta, Asterix, Diamant, Faisalabad red and Sadaf. Moreover, genetic diversity and pathogenicity of Streptomyces spp. on potato tubers were also likely diverse in different geographical regions and also potato cultivars. This study represents a contribution to understanding the local interaction between potatoes and Streptomyces spp. in Pakistan. It will aid in supporting a solution for the management of this pathogen around the world.

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.

Sign in / Sign up

Export Citation Format

Share Document