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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Mycology and Nematology Genetic Diversity and Biology Laboratory » Research » Publications at this Location » Publication #404756

Research Project: Fungal Systematics and Diagnostic Resource Development for Safeguarding Plant Health

Location: Mycology and Nematology Genetic Diversity and Biology Laboratory

Title: Development of a qPCR assay for species-specific detection of the tar spot pathogen Phyllachora maydis

item ROGGENNKAMP, EMILY - Michigan State University
item CHECK, JILL - Michigan State University
item BISWAL, AKSHARA - International Maize & Wheat Improvement Center (CIMMYT)
item FLOYD, CRYSTAL - University Of Minnesota
item MILES, LAURA - Michigan State University
item NICOLLI, CAMILA - University Of Wisconsin
item SHIM, SUJOUNG - Purdue University
item Salgado-Salazar, Catalina
item ALAKONYA, AMOS - International Maize & Wheat Improvement Center (CIMMYT)
item MALVICK, DEAN - University Of Minnesota
item SMITH, DAMON - University Of Wisconsin
item TELENKO, DARCY - Purdue University
item CHILVERS, MARTIN - Michigan State University

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fungi cause many different plant diseases. Sometimes they are quite damaging in terms of losses to producers. One such fungus is Phyllachora maydis, the cause of tarspot of corn, which was first detected in 2015 in the Midwest. Microscopic identification of P. maydis spores is difficult given the indistinct nature and small size of P. maydis spores. This study used DNA diagnostics (amplification and sequencing) to compensate for this difficulty in identification and for earlier detection of this pathogen to help in tar spot predictions and epidemiology. This information will be used by extension personnel, plant breeders, plant pathologists and others engaged in the management of plant diseases.

Technical Abstract: Phyllachora maydis is a fungal plant pathogen that causes tar spot of corn (Zea mays) in North and South America causing devastating yield losses under favorable conditions. Though the disease is relatively easy to diagnose via macroscopic and microscopic observations, other diseases and conditions such as insect frass have been mistaken for tar spot of corn. Furthermore, conidia and ascospores can be difficult to visually distinguish from other fungi, and the development of signs and symptoms of the disease may not be observed until 12 to 20 days after infection. Therefore, a TaqMan quantitative polymerase chain reaction (qPCR) assay was used for detection and quantification of this pathogen. The assay utilized the internal transcribed spacer (ITS) region of P. maydis. The assay was confirmed to distinguish non-target Phyllachora species, corn pathogens, endophytes, from P. maydis samples from several states in the Midwest and from Mexico. The detection limit of this assay was determined to be approximately 100 femtograms (fg) of genomic P. maydis DNA. To demonstrate the robustness of this technology, the assay was tested in different labs using various qPCR thermal cyclers. This assay can be used in downstream research involving latency period, disease prediction, and diagnostics.