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Poster: Diseases of Plants: Disease Detection & Diagnosis


Early detection and quantification of Pseudoperonospora cubensis airborne sporangia using real-time PCR
A. RAHMAN (1), L. Quesada-Ocampo (1) (1) NCSU, U.S.A.

Pseudoperonospora cubensis, the causal agent of cucurbit downy mildew, recently reemerged as a major destructive pathogen of a broad range of crops belonging to the Cucurbitaceae. Airborne sporangia of P. cubensis are the most important source of inoculum to initiate disease as well as cause secondary plant infections. Furthermore, airborne sporangia of this obligate oomycete are known to be able to travel long distances and survive for prolonged periods of time to solar radiation. Therefore, early and rapid detection of the airborne sporangia could serve as a warning for potential disease outbreaks. By designing genome specific primers and using SYBR green-based qPCR method, a preliminary threshold detection level of target pathogen DNA was determined in extracted DNA from P. cubensis sporangia and infected plant tissue. While the method successfully detected up to 5.3 pg/ml of sporangia DNA, the minimum DNA concentration required from infected plant material for successful detection was found to be almost 10-fold higher (69 pg/ml). Using Next Generation Sequencing (NGS) and bioinformatics tools, several unique and conserved candidate genomic regions were also generated to serve as diagnostic genomic markers for P. cubensis. These candidate genomic regions were tested for their suitability as diagnostic markers for detecting and monitoring airborne P. cubensis sporangia inoculum level in the field using real-time qPCR following entrapment with spore traps.