Detection of Airborne Sporangia of Pseudoperonospora cubensis and P. humuli in Michigan Using Burkard Spore Traps Coupled to Quantitative PCR
| Autor: | Julian C Bello, Mary K. Hausbeck, David E Perla, Monique L. Sakalidis |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
0106 biological sciences
0301 basic medicine Oomycete biology Sporangium fungi Plant Science biology.organism_classification 01 natural sciences Spore Fungicide 03 medical and health sciences Horticulture 030104 developmental biology Pseudoperonospora cubensis Downy mildew Agronomy and Crop Science Pathogen Pseudoperonospora humuli 010606 plant biology & botany |
| Zdroj: | Plant Disease. 105:1373-1381 |
| ISSN: | 1943-7692 0191-2917 |
| DOI: | 10.1094/pdis-07-20-1534-re |
| Popis: | Cucurbit downy mildew (CDM), caused by the oomycete pathogen Pseudoperonospora cubensis, is a devastating foliar disease on cucumber resulting in reduced yields. In 2004, the pathogen re-emerged in the United States, infecting historically resistant cucumber cultivars and requiring the adoption of an intensive fungicide program. The pathogen cannot overwinter in Michigan fields but because of an influx of airborne sporangia CDM occurs annually. In Michigan, spore traps are used to monitor the presence of airborne P. cubensis sporangia in cucumber growing regions to guide the initiation of a fungicide program. However, Pseudoperonospora humuli sporangia, the causal agent of downy mildew on hop, are morphologically indistinguishable from P. cubensis sporangia. This morphological similarity reduces the ability to accurately detect P. cubensis from spore trap samples when examined with the aid of light microscopy. To improve P. cubensis detection, we adapted a qPCR-based assay to allow the differentiation between P. cubensis and P. humuli on Burkard spore trap samples collected in the field. Specifically, we evaluated the specificity and sensitivity of P. cubensis detection on Burkard spore trap tapes using a morphological-based and quantitative-PCR (qPCR)-based identification assay and determined whether sporangia of P. cubensis and P. humuli on Burkard samples could be distinguished using qPCR. We found that the qPCR assay was able to detect a single sporangium of each species on spore trap samples collected in the field with Cq values q values of P. cubensis and P. humuli, respectively, suggesting a limited capacity of the qPCR assay for the absolute quantification of sporangia in field samples. After 2 years of monitoring using Burkard spore traps coupled with the qPCR in cucumber fields, P. humuli sporangia were detected more frequently than P. cubensis early in the growing season (May and June). P. cubensis sporangia were detected ∼5 to 10 days before CDM symptoms were first observed in cucumber fields during both years. This research describes an improved sporangial detection system that is key for the monitoring and management of P. cubensis in Michigan. |
| Databáze: | OpenAIRE |
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