Verification of a qPCR Assay for Detection of Phialophora gregata in varied soybean tissues and Brown Stem Rot suspect samples

Abstract

Phialophora gregata is the causal agent of the disease Brown Stem Rot of soybean. As a common pathogen found in fields across Iowa, Iowa State University's Extension & Outreach services, like the Plant & Insect Diagnostic Clinic (PIDC), must have effective methods of detecting and diagnosing the disease so proper management practices can be implemented. P. gregata grows slowly in culture and is difficult to isolate from infected tissues with media, which creates a need for a rapid yet accurate detection method. An article published by Malvick et al. 2007 titled "Detection and Quantification of Phialophora gregata in Soybean and Soil Samples with a Quantitative, Real-Time PCR Assay" presents a promising detection strategy that uses quantitative polymerase chain reaction (qPCR) to detect and quantify P. gregata within a plant sample. This article is the first qPCR assay for P. gregata ever published, which demands the need to evaluate the materials and methods used in the assay to verify the procedure. We tested the reproducibility of Malvick et al. 2007's detection method to examine its effectiveness as a diagnostic tool by determining whether it could detect the pathogen at various concentrations within soybean plants of varying conditions.