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Title: Development of an assay for rapid detection of the lettuce downy mildew pathogen, Bremia lactucae

item KUNJETI, SRIDHARA - University Of California
item CHOI, YOUNG-JOON - Biodiversity And Climate Research Centre (BIK-F)
item Anchieta, Amy
item THINES, MARCO - Biodiversity And Climate Research Centre (BIK-F)
item MICHELMORE, RICHARD - University Of California
item KOIKE, STEVEN - University Of California - Cooperative Extension Service
item TSUCHIDA, CAYLA - University Of California
item Martin, Frank
item SUBBARAO, KRISHNA - University Of California
item Klosterman, Steven

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2015
Publication Date: 8/1/2015
Citation: Kunjeti, S., Choi, Y., Anchieta, A.G., Thines, M., Michelmore, R., Koike, S.T., Tsuchida, C., Martin, F.N., Subbarao, K.V., Klosterman, S.J. 2015. Development of an assay for rapid detection of the lettuce downy mildew pathogen, Bremia lactucae. Phytopathology. Available:

Interpretive Summary:

Technical Abstract: Downy mildew of lettuce, caused by Bremia lactucae, causes chlorosis on leaves and adversely affects marketability. Though downy mildew on lettuce can be controlled by fungicide applications, it is costly to routinely apply fungicides to prevent the establishment of downy mildew. Repeated use of the chemicals also can lead to fungicide resistance in the pathogen. To specifically detect Bremia lactucae for the purpose of developing an early warning system, we designed a quantitative real-time PCR (qPCR) assay based on a mitochondrial DNA sequence unique to Bremia lactucae. Specificity tests revealed that the qPCR assay is specific for detection of B. lactucae and not related Bremia species. This assay is sensitive, enabling detection of very low levels of inoculum that may be present in the field. Early detection of the pathogen, coupled with knowledge of other factors that favor downy mildew outbreaks, may enable disease forecasting for judicious timing of fungicide applications.