Differential Production of Thaxtomins by Pathogenic<i>Streptomyces</i>Species In Vitro

Loria, Rosemary; Bukhalid, Raghida; Creath, R. A.; Leiner, R. H.; Olivier, M.; Steffens, Johann C.

doi:10.1094/phyto-85-537

Cited by 128 publications

(107 citation statements)

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“…The study with IAA supplement further suggested that the effect may be dosage dependent, as only the greatest rate was effective in significantly reducing thaxtomin A toxicity. This may represent a reduced efficiency of pathogen invasion and disease development, as thaxtomin A aids this penetration from cell to cell (24,25). Indirect evidence (7) supports these findings with application of auxin to potato disks reducing tuber browning when inoculated with S. scabiei.…”

Section: Discussionmentioning

confidence: 93%

“…Furthermore, the strains G#32 and G#10 were also grown in 500 ml of oatmeal liquid broth (24) in 1-liter Erlenmeyer flasks amended with the same 2,4-D treatments and controls. Each treatment was replicated three times with flasks incubated on a shaker (160 rpm) in darkness at 30°C.…”

Section: Methodsmentioning

confidence: 99%

“…Each treatment was replicated three times with flasks incubated on a shaker (160 rpm) in darkness at 30°C. After 3 weeks, thaxtomin A was extracted and concentrated in chloroform, as described by Loria et al (24), and thaxtomin A content was determined.…”

Section: Methodsmentioning

confidence: 99%

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Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity

et al. 2008

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Production of the phytotoxin thaxtomin A by pathogenic Streptomyces spp. is essential for induction of common scab disease in potato. Prior studies have shown that foliar application of sublethal concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and other auxin or auxin-like compounds significantly reduced severity and occurrence of common scab in subsequently produced tubers. However, the means of disease suppression by these compounds was not known. We confirm the disease suppressive activity of 2,4-D. Detailed tuber physiological examination showed that lenticel numbers, lenticel external dimensions, and periderm thickness and structure, physiological features believed to be critical to Streptomyces scabiei infection, were not substantially changed by 2,4-D treatments, negating a possible mechanism for disease suppression through alteration of these structures. In contrast, our studies show accumulation of 2,4-D in tubers of treated plants occurs and is associated with an enhanced tolerance to thaxtomin A. Applying 2,4-D to cultures of S. scabiei did not significantly alter in vitro growth of the pathogen. Thaxtomin A production by the pathogen was inhibited by 2,4-D, but only at the highest rate tested (1.0 mM), which is at least 200-fold more than is found in 2,4-D treated tubers. These data suggest 2,4-D has no direct effect on the pathogen or its virulence. Confirmatory evidence from studies with Arabidopsis thaliana seedlings demonstrated that the auxins 2,4-D and IAA ameliorate thaxtomin A toxicity. The evidence presented whereby auxin treatment inhibits toxicity of thaxtomin A secreted by the pathogen suggests a novel indirect means of disease suppression.

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Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

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Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity

et al. 2008

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“…Thaxtomin A (Figure 1) is a phytotoxin produced by several species of the gram-positive filamentous bacteria in the genus Streptomyces (including S. scabie s, S. acidiscabies , and S. turgidiscabies ) that cause scab disease in potato and in several taproot crops such as radish and turnip (King et al, 1989(King et al, , 1991Lawrence et al, 1990;Loria et al, 1995Loria et al, , 1997Miyajima et al, 1998). Potato scab is a disease of major economic importance in most potato-producing areas of the world (Lambert and Loria, 1989).…”

Section: Introductionmentioning

confidence: 99%

“…The genes that encode the thaxtomin biosynthetic pathway appear to lie on a pathogenicity island that was transmitted to Streptomyces species, resulting in the emergence of new pathogenic species in agricultural production systems (Healy et al, 1999(Healy et al, , 2000Bukhalid et al, 2002). The pathogenicity of various S. scabies isolates is correlated with their ability to produce thaxtomin A (King et al, 1991;Loria et al, 1995;Goyer et al, 1998;Kinkel et al, 1998). Mutant S. scabies strains that are avirulent or have reduced virulence exhibit decreased or undetectable levels of thaxtomin A relative to the parent strain (Healy et al, 1997;Goyer et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

An Arabidopsis Mutant Resistant to Thaxtomin A, a Cellulose Synthesis Inhibitor fromStreptomycesSpecies[W]

et al. 2003

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Thaxtomin A is a phytotoxin produced by Streptomyces scabies and other Streptomyces species, the causative agents of common scab disease in potato and other taproot crops. At nanomolar concentrations, thaxtomin causes dramatic cell swelling, reduced seedling growth, and inhibition of cellulose synthesis in Arabidopsis. We identified a mutant of Arabidopsis, designated txr1 , that exhibits increased resistance to thaxtomin as a result of a decrease in the rate of toxin uptake. The TXR1 gene was identified by map-based cloning and found to encode a novel, small protein with no apparent motifs or organelle-targeting signals. The protein, which has homologs in all fully sequenced eukaryotic genomes, is expressed in all tissues and during all developmental stages analyzed. Microarray transcript profiling of some 14,300 genes revealed two stomatin-like genes that were expressed differentially in the txr1 mutant and the wild type. We propose that TXR1 is a regulator of a transport mechanism.

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United States Department of Agriculture–Agricultural Research Service research on natural products for pest management

Duke¹,

Baerson²,

Dayan³

et al. 2003

Pest Management Science

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Recent research of the Agricultural Research Service of USDA on the use of natural products to manage pests is summarized. Studies of the use of both phytochemicals and diatomaceous earth to manage insect pests are discussed. Chemically characterized compounds, such as a saponin from pepper (Capsicum frutescens L), benzaldehyde, chitosan and 2-deoxy-D-glucose are being studied as natural fungicides. Resin glycosides for pathogen resistance in sweet potato and residues of semi-tropical leguminous plants for nematode control are also under investigation. Bioassay-guided isolation of compounds with potential use as herbicides or herbicide leads is underway at several locations. New natural phytotoxin molecular target sites (asparagine synthetase and fructose-1,6-bisphosphate aldolase) have been discovered. Weed control in sweet potato and rice by allelopathy is under investigation. Molecular approaches to enhance allelopathy in sorghum are also being undertaken. The genes for polyketide synthases involved in production of pesticidal polyketide compounds in fungi are found to provide clues for pesticide discovery. Gene expression profiles in response to fungicides and herbicides are being generated as tools to understand more fully the mode of action and to rapidly determine the molecular target site of new, natural fungicides and herbicides.

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Differential Production of Thaxtomins by PathogenicStreptomycesSpecies In Vitro

Cited by 128 publications

References 0 publications

Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity

Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity

An Arabidopsis Mutant Resistant to Thaxtomin A, a Cellulose Synthesis Inhibitor fromStreptomycesSpecies[W]

United States Department of Agriculture–Agricultural Research Service research on natural products for pest management

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