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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #146993
Title: COMPARISON BETWEEN ISOLATION AND PCR FOR DETECTION OF XANTHOMONAS CITRI IN NEW LESIONS ON IMMATURE CITRUS LEAVES AND OLD LESIONS ON MATURE CITRUS LEAVES IN THAILAND

Author
item LERTSUCHATAVANICH, U. - KASETSART UNIV.
item THAVEECHAI, N. - KASETSART UNIV.
item PARADORNUWAT, A. - KASETSART UNIV.
item Schaad, Norman

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2003
Publication Date: 6/1/2003
Citation: Schaad, N.W., Postnikova, E., Fatmi, M., Lacy, G. Chang, C.J. 2003. Xylessa fastidiosa taxonomy. Phytopathology. 93:S76.

Interpretive Summary:

Technical Abstract: Citrus canker, caused by Xc, is widespread in Asia. Canker is not established in the US and is highly regulated. The reliability of real-time PCR was compared to classical isolation on agar media for detection of Xc in new lesions on immature leaves and old lesions on mature leaves. New lesions were 1- mm or less in diameter, surrounded by chlorosis, with no visible hyperplasia. The larger, old lesions had hyperplasia. A portion of each lesion was removed, soaked in 50ul water and after 20 min., a loop-full streaked onto FS agar plates. Duplicate 1ul samples were assayed by real-time PCR in a Smart Cycler. Of 13 new lesions, 7 (54%) were positive by PCR and 8 (62%) by isolation. With old lesions, 15/26 (58%) were positive by PCR but only 9/26 (35%) by isolation. All suspect Xc cultures were pathogenic. These results show that PCR correlates highly with isolations for new lesions but not for old lesions. Apparently old lesions contain few viable cells and, most likely, contribute less to spread of the disease.