Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/1998
Publication Date: N/A
Interpretive Summary: Leaf scald, a major disease of sugarcane, recently increased in incidence in Florida. Although the disease has characteristic symptoms, sugarcane can be latently infected without any symptoms. Methodology was required to detect latently infected sugarcane. A BIO-PCR assay was developed that detected Xanthomonas albilineans, the leaf scald pathogen. The method was specific for the leaf scald pathogen; other closely related species and other sugarcane inhabiting bacteria were not detected. Although this method was slightly less sensitive than isolation, it was quicker and automatically verified taxonomy identity. The BIO-PCR assay is much more sensitive than the serological methods used in many quarantines, Therefore, the method is suitable for quarantines that require accurate detection of low pathogen populations. The BIO-PCR technique will also allow certain research to be conducted that would not previously be possible and should benefit sugarcane pathology.
Technical Abstract: Polymerase chain reaction (PCR) primers, XAF1/XAR1, were selective in detecting Xanthomonas albilineans, the causal agent of leaf scald of sugarcane. The efficiency and reliability of PCR were compared to dot immunobinding assay (DIA), ELISA, and classical isolation techniques for detecting Xanthomonas albilineans in suspensions of pure cells and extracts of field collected stalk and leaf samples of sugarcane. In addition, classical PCR and BIO-PCR (biological amplification followed by PCR) were compared to isolation on a semiselective agar medium. Classical PCR and BIO-PCR techniques had the advantage of not requiring pathogenicity to confirm the identity of colonies tentatively identified as X. albilineans on the semiselective medium. Isolation and BIO-PCR techniques were the most sensitive; however, BIO-PCR needed half the incubation time. Thus, the BIO-PCR technique was almost as sensitive as isolation while it required less time and provided taxonomic confirmation.