Detection of Pythium ultimum Using Polymerase Chain Reaction with Species-Specific Primers

Area of Science:

• Plant Pathology
• Molecular Biology
• Mycology

Background:

• Pythium ultimum is a significant oomycete pathogen causing damping-off disease in seedlings.
• Accurate and rapid detection of P. ultimum is crucial for effective disease management.

Purpose of the Study:

• To sequence the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region of Pythium ultimum and Pythium group HS.
• To design species-specific primers for polymerase chain reaction (PCR)-based detection.
• To develop a PCR method for detecting P. ultimum from diseased seedlings.

Main Methods:

• Sequencing of the rDNA ITS region for P. ultimum and Pythium group HS.
• Design and application of species-specific primers (K1+K3) for PCR.
• Optimization of PCR conditions using DNA extracts from diseased seedlings, including inhibitor dilution with Tris-EDTA (TE) buffer.

Main Results:

• The ITS sequences of P. ultimum and Pythium group HS were identical, supporting the classification of the HS group as an asexual strain of P. ultimum.
• The designed primer pair K1+K3 specifically amplified P. ultimum and the HS group, but not 20 other Pythium species.
• PCR successfully detected P. ultimum from a single diseased seedling after optimizing DNA extraction and PCR inhibition mitigation.

Conclusions:

• The study successfully developed and validated species-specific primers for the detection of Pythium ultimum.
• The optimized PCR method allows for the sensitive and specific identification of P. ultimum from infected plant material.
• This molecular tool can aid in the early diagnosis and management of Pythium-induced seedling diseases.