Efficient multiplex simple sequence repeat genotyping of the oomycete plant pathogen Phytophthora infestans

Area of Science:

• * Molecular Biology
• * Population Genetics
• * Plant Pathology

Background:

• * Accurate genotyping is crucial for understanding pathogen population dynamics.
• * Existing methods for Phytophthora infestans genotyping can be time-consuming and costly.
• * High-throughput screening is essential for global pathogen surveillance.

Purpose of the Study:

• * To develop a rapid, cost-effective, one-step multiplex PCR assay for genotyping Phytophthora infestans.
• * To optimize conditions for high-throughput screening using capillary electrophoresis.
• * To enable the analysis of diverse pathogen populations, including those with mixed ploidy levels.

Main Methods:

• * Selection and optimization of twelve informative simple sequence repeat (SSR) markers.
• * Development of a one-step multiplex PCR protocol with optimized primers, fluorescent labels, and PCR conditions.
• * Utilized capillary electrophoresis with four fluorescent labels and a size standard for fragment analysis.
• * Standardization of the protocol across two international laboratories.

Main Results:

• * The multiplex PCR assay demonstrated high accuracy and agreement with simplex reactions.
• * The method successfully resolved distinct multilocus genotypes (MLGs) in thousands of Phytophthora infestans isolates.
• * The assay detected varying ploidy levels within isolates, with methods developed for mixed ploidy analysis.
• * Direct genotyping from infected field material was achieved, streamlining sample processing.

Conclusions:

• * The developed one-step multiplex PCR assay provides a robust and efficient tool for global Phytophthora infestans population analysis.
• * This method facilitates high-throughput screening and enhances the accuracy of pathogen diversity studies.
• * Standardization and international collaboration are key to building comprehensive pathogen databases and understanding global disease dynamics.