A molecular method to assess Phytophthora diversity in environmental samples.

Area of Science:

• Plant Pathology
• Molecular Biology
• Environmental Microbiology

Background:

• Current molecular detection methods for Phytophthora are limited to specific species, posing challenges for ecological research and plant health legislation.
• A genus-wide detection method is needed to accurately assess Phytophthora diversity in environmental samples.

Purpose of the Study:

• To develop and validate a novel molecular approach for detecting multiple Phytophthora species in soil and water samples.
• To design and test genus-specific primers targeting the internal transcribed spacer (ITS) regions of Phytophthora DNA.

Main Methods:

• Developed genus-specific primers targeting ITS regions for Phytophthora detection.
• Tested two primer sets: a long product (LP) assay and a short product (SP) assay.
• Validated the method using soil and water samples from Scotland, comparing on-site sampling with laboratory-based centrifugation.

Main Results:

• The SP assay demonstrated higher sensitivity and reliability in detecting Phytophthora species without cross-reacting with Pythium.
• Identified 15 distinct Phytophthora phylotypes across ITS clades 1, 2, 3, 6, 7, and 8.
• Detected up to three and five different Phytophthora phylotypes in single soil and water samples, respectively, with ITS-clade 6 (P. gonapodyides-like) being most frequent.

Conclusions:

• The new molecular method effectively detects multiple Phytophthora species, including unknown ones, in environmental samples.
• This approach offers significant advantages for ecological studies, biosecurity, and commercial testing of soil and water.
• The developed primers and methods enhance the ability to monitor Phytophthora diversity and potential plant pathogens.