[Verification Study of the Detection Method for Unauthorized Genetically Modified Papaya by Combining DNA Polymerases...

Area of Science:

• Molecular Biology
• Food Science
• Genetics

Context:

• Official Japanese methods for detecting unauthorized genetically modified (GM) papayas utilize real-time PCR with specific DNA polymerases.
• Previous studies indicated potential false negatives in detecting the PRSV-YK GM papaya line using TaqMan Gene Master Mix.
• This highlights a need to evaluate the performance of different reagents and instruments across various unauthorized GM papaya lines.

Purpose:

• To assess the impact of two DNA polymerases (TaqMan Gene and FastGene) and three real-time PCR instruments (ABI7500, QS12K, LC480) on the limits of detection (LOD) for unauthorized GM papaya lines (PRSV-YK, PRSV-SC, PRSV-HN).
• To evaluate the detection of cauliflower mosaic virus 35S promoter (CaM) and a papaya positive control (Chy).
• To identify optimal reagent and instrument combinations to prevent false negatives in GM papaya detection.

Summary:

• Detection tests for PRSV-YK and PRSV-SC unauthorized GM papayas using the ABI7500 and QS12K systems showed higher LOD with TaqMan Gene Master Mix compared to FastGene.
• This occurred when the amplification curve did not cross the threshold line, preventing accurate Cq value determination.
• No significant LOD differences were observed for PRSV-HN, CaM, Chy detection, or with the LC480 instrument, regardless of the DNA polymerase used.

Impact:

• Recommends using FastGene DNA polymerase with the ABI7500 or QS12K systems for PRSV-YK and PRSV-SC detection to avoid false negatives in low-level GM papaya contamination.
• Ensures more reliable detection of unauthorized GM papayas, crucial for food safety and regulatory compliance.
• Provides critical data for optimizing GM detection protocols, potentially reducing trade barriers and enhancing consumer trust.