Development of Real-Time and Conventional PCR Assays for Identifying Stubby Root Nematode Paratrichodorus allius

Paratrichodorus allius is an important pest on many crops, particularly on potato due to its ability to transmit Tobacco rattle virus causing corky ringspot disease on tubers. Detection and identification of P. allius are important for effective disease management. In this study, a rapid and reliable molecular diagnosis of this nematode targeting internal transcribed spacer ribosomal DNA was established. The specificity of the designed primers was evaluated using 29 nematode species and results showed that a single amplicon was produced from DNA of P. allius only. Detection sensitivity analysis indicated that a 9.6 × 10−4 ng of DNA template could be detected by conventional PCR and 1.92 × 10−4 ng of DNA by real-time PCR. The PCR assays amplified DNA of stubby root nematodes isolated from 18 soil samples in North Dakota and Minnesota, which were confirmed as P. allius by sequencing. Both conventional PCR and real-time PCR assays amplified target nematodes from complex nematode communities, supporting the success of this molecular diagnosis of P. allius. This is the first report of P. allius identification using the real-time PCR method and from nematode communities with other nematodes using conventional PCR. The new PCR assays provide rapid species identification and are suitable for use in diagnostic laboratories and detection of field infestations with P. allius.

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Development of Real-Time and Conventional PCR Assays for Identifying a Newly Named Species of Root-Lesion Nematode (Pratylenchus dakotaensis) on Soybean

International Journal of Molecular Sciences ◽

10.3390/ijms22115872 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5872

Author(s):

Intiaz Amin Chowdhury ◽

Guiping Yan

Keyword(s):

North Dakota ◽

Real Time ◽

Real Time Pcr ◽

Detection Sensitivity ◽

Root Lesion Nematode ◽

Conventional Pcr ◽

Cycle Number ◽

Lesion Nematode ◽

Pcr Assays ◽

Species Specific

A rapid and accurate PCR-based method was developed in this study for detecting and identifying a new species of root-lesion nematode (Pratylenchus dakotaensis) recently discovered in a soybean field in North Dakota, USA. Species-specific primers, targeting the internal transcribed spacer region of ribosomal DNA, were designed to be used in both conventional and quantitative real-time PCR assays for identification of P.dakotaensis. The specificity of the primers was evaluated in silico analysis and laboratory PCR experiments. Results showed that only P.dakotaensis DNA was exclusively amplified in conventional and real-time PCR assays but none of the DNA from other control species were amplified. Detection sensitivity analysis revealed that the conventional PCR was able to detect an equivalent to 1/8 of the DNA of a single nematode whereas real-time PCR detected an equivalent to 1/32 of the DNA of a single nematode. According to the generated standard curve the amplification efficiency of the primers in real-time PCR was 94% with a R2 value of 0.95 between quantification cycle number and log number of P.dakotaensis. To validate the assays to distinguish P.dakotaensis from other Pratylenchus spp. commonly detected in North Dakota soybean fields, 20 soil samples collected from seven counties were tested. The PCR assays amplified the DNA of P.dakotaensis and discriminated it from other Pratylenchus spp. present in North Dakota soybean fields. This is the first report of a species-specific and rapid PCR detection method suitable for use in diagnostic and research laboratories for the detection of P.dakotaensis.

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Potential pitfalls in the quantitative molecular detection ofEscherichia coliO157:H7 in environmental matrices

Canadian Journal of Microbiology ◽

10.1139/w05-149 ◽

2006 ◽

Vol 52 (5) ◽

pp. 482-488 ◽

Cited By ~ 25

Author(s):

Rebekka R.E Artz ◽

Lisa M Avery ◽

Davey L Jones ◽

Ken Killham

Keyword(s):

Escherichia Coli ◽

Real Time ◽

Real Time Pcr ◽

Environmental Samples ◽

Detection Sensitivity ◽

Escherichia Coli O157 ◽

Soil System ◽

E Coli ◽

Animal Wastes ◽

Pcr Assays

The detection sensitivity and potential interference factors of a commonly used assay based on real-time polymerase chain reaction (PCR) for Escherichia coli O157:H7 using eae gene-specific primers were assessed. Animal wastes and soil samples were spiked with known replicate quantities of a nontoxigenic strain of E. coli O157:H7 in a viable or dead state and as unprotected DNA. The detection sensitivity and accuracy of real-time PCR for E. coli O157:H7 in animal wastes and soil is low compared to enrichment culturing. Nonviable cells and unprotected DNA were shown to produce positive results in several of the environmental samples tested, leading to potential overestimates of cell numbers due to prolonged detection of nonviable cells. This demonstrates the necessity for the specific calibration of real-time PCR assays in environmental samples. The accuracy of the eae gene–based detection method was further evaluated over time in a soil system against an activity measurement, using the bioluminescent properties of an E. coli O157:H7 Tn5luxCDABE construct. The detection of significant numbers of viable but nonculturable (VBNC) as well as nonviable and possibly physically protected cells as shown over a period of 90 days further complicates the use of real-time PCR assays for quick diagnostics in environmental samples and infers that enrichment culturing is still required for the final verification of samples found positive by real-time PCR methods.Key words: Escherichia coli O157:H7, real-time PCR, animal waste, soil, VBNC.

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A New Highly Sensitive and Specific Real-Time PCR Assay Targeting the Malate Dehydrogenase Gene ofKingella kingaeand Application to 201 Pediatric Clinical Specimens

Journal of Clinical Microbiology ◽

10.1128/jcm.00505-18 ◽

2018 ◽

Vol 56 (8) ◽

Cited By ~ 3

Author(s):

Nawal El Houmami ◽

Guillaume André Durand ◽

Janek Bzdrenga ◽

Anne Darmon ◽

Philippe Minodier ◽

...

Keyword(s):

Real Time ◽

Malate Dehydrogenase ◽

Real Time Pcr ◽

Detection Sensitivity ◽

Rt Pcr ◽

Pcr Assay ◽

Content Type ◽

Clinical Specimens ◽

Specificity And Sensitivity ◽

Pcr Assays

ABSTRACTKingella kingaeis a significant pediatric pathogen responsible for bone and joint infections, occult bacteremia, and endocarditis in early childhood. Past efforts to detect this bacterium using culture and broad-range 16S rRNA gene PCR assays from clinical specimens have proven unsatisfactory; therefore, by the late 2000s, these were gradually phased out to explore the benefits of specific real-time PCR tests targeting thegroELgene and the RTX locus ofK. kingae. However, recent studies showed that real-time PCR (RT-PCR) assays targeting theKingellasp. RTX locus that are currently available for the diagnosis ofK. kingaeinfection lack specificity because they could not distinguish betweenK. kingaeand the recently describedKingella negevensisspecies. Furthermore,in silicoanalysis of thegroELgene from a large collection of 45K. kingaestrains showed that primers and probes fromK. kingaegroEL-based RT-PCR assays display a few mismatches withK. kingae groELvariations that may result in decreased detection sensitivity, especially in paucibacillary clinical specimens. In order to provide an alternative togroEL- and RTX-targeting RT-PCR assays that may suffer from suboptimal specificity and sensitivity, aK. kingae-specific RT-PCR assay targeting the malate dehydrogenase (mdh) gene was developed for predicting no mismatch between primers and probe and 18 variants of theK. kingae mdhgene from 20 distinct sequence types ofK. kingae. This novelK. kingae-specific RT-PCR assay demonstrated high specificity and sensitivity and was successfully used to diagnoseK. kingaeinfections and carriage in 104 clinical specimens from children between 7 months and 7 years old.

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