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United States Department of Agriculture

Agricultural Research Service

Title: A Combined Agar Absorbent and Bio-Pcr Assay for Rapid, Sensitive Detection of Xylella Fastidiosa (Xf) in Grape and Citrus

item Fatmi, M. - INST. AGR. VET. HASSAN II
item Damsteegt, Vernon
item Schaad, Norman

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2003
Publication Date: June 1, 2003
Citation: Fatmi, M., Damsteegt, V.D., Schaad, N.W. 2003. A combined agar absorbent and BIO-PCR assay for rapid, sensitive detection of Xylella fastidiosa (XF) in grape and citrus. Phytopathology. 93:S25.

Technical Abstract: Application of PCR for disease diagnosis has been limited by the presence of PCR inhibitors. Inhibition can be overcome and sensitivity increased with BIO-PCR by enriching bacteria on agar media, however, Xf grows slowly. We have developed an efficient agar absorbent BIO-PCR assay for detecting Xf in grape and citrus plants. By spotting symptomatic grape petioles and citrus leaf veins onto PD2 agar, we found 43% of the grape and 100% of the citrus samples were positive after a 1 or 4 h absorption treatment. All grape samples were positive after 5 days with BIO-PCR. Two of 6 citrus and none of 12 grape samples were positive by direct PCR conducted at spotting. Viable Xf were recovered from all samples after 14 d growth on PD2. For routine assays, we recommend touching tissue to the bottom of a microfuge tube for direct real-time PCR and to each of four PD2 agar microfuge tubes. After one h, add 50 ul of PCR water to two tubes, vortex, and use 5ul for real-time PCR. If negative, assay the other two tubes after 5 days enrichment.

Last Modified: 4/19/2015
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