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United States Department of Agriculture

Agricultural Research Service

Title: Reliability of Real-Time Pcr for Detecting and Quantifying Xanthomonas Axonopodis Pv Citri in Wind Driven Splash

item Mavrodieva, V. A. - NCSU/USDA-APHIS-CPHST
item Parker, P. E. - USDA-APHIS
item Levy, L. - USDA-APHIS-CPHST
item Gottwald, Timothy

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2005
Publication Date: June 1, 2005
Citation: Bock, C., Mavrodieva, V., Parker, P., Levy, L., Gottwald, T.R. 2005. Reliability of real-time pcr for detecting and quantifying xanthomonas axonopodis pv citri in wind driven splash. Phytopathology. 95(6):S11.

Technical Abstract: The bacterium <i>Xanthomonas axonopodis pv citri</i> causes citrus canker and is under eradication in Florida. Identifying and quantifying bacteria is useful when investigating the epidemiology of the pathogen and can have application in monitoring dispersal of the bacteria. In a series of experiments using field collected samples dilution plating was compared with SYBR Green real-time PCR using citrus canker universal primers VM3+4 for pathogen detection (no sample concentration was performed). Of 314 samples tested, 235 (75%) were in agreement. False negatives using PCR were found in 75 (28%) samples which contained 3 to 863 bacteria/ml, using dilution plating. Only 4 samples (1.5%) were positive using PCR, but not by culture. All samples with >863 bacteria per ml were detected using both methods. There was a positive linear relationship between the real-time PCR score and log number of bacteria collected per ml (0 to1.0x10<sup>5</sup>, R<sup>2</sup> of 0.72). Real-time PCR has been reported to reliably detect 10<sup>3</sup> bacteria per ml, which is confirmed by these results using field collected samples, although it was not consistent at quantifying the pathogen as measured against dilution plating.

Last Modified: 4/17/2015
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