Using the txtAB operon to quantify pathogenic Streptomyces in potato tubers and soil

Xinshun Qu, Leslie A. Wanner, Barbara Jane Christ

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The phytotoxin thaxtomin, produced by plant pathogenic Streptomyces species, is the only known pathogenicity determinant for common scab diseases of potato and other root and tuber crops. Genes encoding thaxtomin synthetase (txtAB) are found on a pathogenicity island characteristic of genetically diverse plant pathogenic Streptomyces species. In this study, an SYBR Green quantitative real-time polymerase chain reaction (PCR) assay using primers designed to anneal to the txtAB operon of Streptomyces was developed to quantify pathogenic bacterial populations in potatoes and soil. The real-time PCR assay was specific for pathogenic Streptomyces strains. The detection limit of the assay was 10 fg of the target DNA, or one genome equivalent. Cycle threshold (Ct) values were linearly correlated with the concentration of the target DNA (correlation coefficient R2 = 0.99) and were not affected by the presence of plant DNA extracts, indicating the usefulness of the assay for quantitative analyses of the pathogenic bacteria in plant tissues. The amount of pathogenic Streptomyces DNA in total DNA extracts from 1 g asymptomatic and symptomatic tubers was quantified using the assay and ranged from 101 to 106 pg. A standard curve was established to quantify pathogenic Streptomyces in soil. Using the standard curve, numbers of pathogenic Streptomyces colony forming units were extrapolated to range from 103 to 106 per gram of soil from potato fields where common scab was found. This real-time PCR assay using primers designed from the txtAB operon allows rapid, accurate, and cost effective quantification of pathogenic Streptomyces strains in potato tubers and in soil.

Original languageEnglish (US)
Pages (from-to)405-412
Number of pages8
JournalPhytopathology
Volume98
Issue number4
DOIs
StatePublished - Apr 1 2008

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Streptomyces
operon
tubers
potatoes
soil
assays
DNA
quantitative polymerase chain reaction
scab diseases
pathogenicity islands
phytotoxins
extracts
ligases
plant tissues
detection limit
pathogenicity
genome
bacteria
crops

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Plant Science

Cite this

Qu, Xinshun ; Wanner, Leslie A. ; Christ, Barbara Jane. / Using the txtAB operon to quantify pathogenic Streptomyces in potato tubers and soil. In: Phytopathology. 2008 ; Vol. 98, No. 4. pp. 405-412.
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Using the txtAB operon to quantify pathogenic Streptomyces in potato tubers and soil. / Qu, Xinshun; Wanner, Leslie A.; Christ, Barbara Jane.

In: Phytopathology, Vol. 98, No. 4, 01.04.2008, p. 405-412.

Research output: Contribution to journalArticle

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