Comparison of PCR, BIO-PCR, DIA, ELISA and isolation on semiselective medium for detection of Xanthomonas albilineans, the causal agent of leaf scaldof sugarcane

Polymerase chain reaction (PCR) and newly designed primers, XAF1/XAR1, were tested for selective detection of the causal agent of leaf scald of sugarc ane, Xanthomonas albilineans. The efficiency and reliability of PCR were co mpared with dot immunobinding assay (DIA), ELISA and classical isolation te chniques for detecting X. albilineans in suspensions of pure cells and extr acts of field-collected stalk and leaf samples of sugarcane. In addition, c lassical PCR and BIO-PCR (biological amplification followed by PCR) were co mpared with isolation on a semiselective agar medium. Classical PCR and BIO -PCR techniques had the advantage of not requiring pathogenicity tests to c onfirm the identity of colonies tentatively identified as X, albilineans on modified semiselective XAM agar medium. The m-XAM medium and BIO-PCR techn iques were the most sensitive; however, the former required seven days wher eas the latter required only four days. The BIO-PCR technique was as sensit ive as the semiselective medium technique and eliminated the need to conduc t any additional tests to confirm the identification.