An Internal Reaction Control for Routine Detection of Clavibacter michiganensis subsp. sepedonicus Using a Real-Time...

Area of Science:

• Plant Pathology
• Molecular Biology
• Biotechnology

Background:

• Bacterial ring rot, caused by Clavibacter michiganensis subsp. sepedonicus, poses a significant threat to potato crops.
• Accurate and reliable detection methods are crucial for managing this disease.
• TaqMan real-time PCR offers high sensitivity but requires robust controls to ensure result validity.

Purpose of the Study:

• To develop and validate an internal reaction control for TaqMan PCR to detect Clavibacter michiganensis subsp. sepedonicus.
• To assess the control's impact on assay sensitivity, specificity, and its ability to detect inhibitors.
• To facilitate the routine application of TaqMan real-time PCR in diagnostic testing.

Main Methods:

• Integration of a non-target sequence cloned into a plasmid as an internal control in a TaqMan PCR assay.
• Utilizing SYBR Green for melt analysis to differentiate between the control and target amplicons.
• Testing the assay's performance in the presence of known inhibitors like guanidine-HCl and humic acid.

Main Results:

• The internal control did not affect the limit of detection or specificity of the Clavibacter michiganensis subsp. sepedonicus assay.
• Melt analysis effectively distinguished the control amplicon (242 bp, ~94.5°C) from the target amplicon (152 bp, ~85.5°C).
• The control detected inhibition by guanidine-HCl and humic acid at lower concentrations than the target, establishing a quantitative threshold for inhibitor detection.

Conclusions:

• The integrated internal reaction control enhances the reliability of TaqMan real-time PCR for Clavibacter michiganensis subsp. sepedonicus detection.
• This control enables validation of negative results and effective detection of PCR inhibition in diagnostic samples.
• The method supports the routine use of TaqMan real-time PCR in potato disease diagnostics.