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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #361811

Research Project: Management of Pathogens for Strawberry and Vegetable Production Systems

Location: Crop Improvement and Protection Research

Title: Improved detection methods for the spinach downy mildew pathogen, Peronospora effusa

item BATISTA DA SILVA, MYCHELE - University Of California
item CHOI, YOUNG-JOON - Kunsan National University
item Martin, Frank
item OSORIO MARIN, JULIANA - University Of California
item GARCIA-LLANOS, ARMANDO - University Of California
item VAN DEYNZE, ALLEN - University Of California
item Klosterman, Steven

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/9/2019
Publication Date: 8/6/2019
Citation: Batista Da Silva, M., Choi, Y., Martin, F.N., Osorio Marin, J., Garcia-Llanos, A., Van Deynze, A., Klosterman, S.J. 2019. Improved detection methods for the spinach downy mildew pathogen, Peronospora effusa. American Phytopathological Society Annual Meeting, August 3-7, 2019, Cleveland, Ohio.

Interpretive Summary:

Technical Abstract: Peronospora effusa is an obligate oomycete pathogen, and the causal agent of spinach downy mildew. Spinach downy mildew results in losses of up to 30% or higher in organic spinach production. Control options for this disease in organic production are limited to the development of disease resistant cultivars since fungicides are not available to use in organic production. Different pathotypes of P. effusa have been identified using a list of differential cultivars. There is a continuous need to update the differentials due to the quick evolution of the pathogen. Early detection of the pathogen, especially in the field and its associated different pathotypes, can contribute to improved management strategies in both conventional and organic spinach production. We currently are testing a recombinase polymerase amplification assay (RPA) to detect the pathogen in the field. The RPA assay process works at low constant temperature due to a stabilizing enzyme and the use of specific primers. We designed and further tested two sets of primers and a qPCR probe based on a mitochondrial gene locus for specific detection of P. effusa. The assay was tested on DNA template from 40 different isolates of P. effusa and eight closely-related species. Using this approach, one primer and probe set tested led to specific amplification of only P. effusa DNA. Using the primers only, without the qPCR probe, nonspecific detection of DNA from related species such as P. obovata and P. lepigoni was possible. The next step is to adapt the P. effusa-specific probe to in-field RPA-based detection.