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Title: Detection of the downy mildew pathogens of spinach (Peronospora effusa) and beet (P. schachtii) using spore traps and quantitative PCR assays

Author
item Klosterman, Steven
item Anchieta, Amy
item MCROBERTS, NEIL - University Of California
item KOIKE, STEVEN - University Of California - Cooperative Extension Service
item SUBBARAO, KRISHNA - University Of California
item VOGLMAYR, HERMANN - University Of Vienna
item CHOI, YOUNG-JOON - Biodiversity And Climate Research Centre (BIK-F)
item THINES, MARCO - Biodiversity And Climate Research Centre (BIK-F)
item Martin, Frank

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2014
Publication Date: 8/9/2014
Citation: Klosterman, S.J., Anchieta, A.G., Mcroberts, N., Koike, S.T., Subbarao, K.V., Voglmayr, H., Choi, Y., Thines, M., Martin, F.N. 2014. Detection of the downy mildew pathogens of spinach (Peronospora effusa) and beet (P. schachtii) using spore traps and quantitative PCR assays [abstract]. American Phytopathological Society. Available: http://www.apsnet.org/meetings/Documents/2014_meeting_abstracts/aps2014abO50.htm.

Interpretive Summary:

Technical Abstract: Downy mildew of spinach, caused by Peronospora effusa, is a disease constraint on spinach production worldwide. The aim of this study was to develop a real-time quantitative PCR assay for detection of airborne inoculum of P. effusa in California. This type of assay may, in combination with disease-conducive weather forecasting, be helpful to time fungicide applications for disease management. Among oomycete ribosomal DNA (rDNA) sequences examined, the highest nucleotide sequence identity was observed between rDNA sequences of P. effusa and Peronospora schachtii, the cause of downy mildew on Beta vulgaris (beet and Swiss chard). Single nucleotide polymorphisms (SNPs) were detected between P. effusa and P. schachtii 18S rDNA regions for design of P. effusa- and P. schachtii-specific TaqMan probes and reverse primers. An allele-specific probe and primer amplification method was applied to determine the frequency of both P. effusa and P. schachtii rDNA target sequences in pooled DNA samples, enabling quantification of rDNA of P. effusa from impaction spore trap samples. The rDNA copy numbers of P. effusa were on average 3400-fold higher from trap samples collected near an infected spinach field than at sites remote from such fields.