DETECTION OF THE SUGARCANE LEAF SCALD PATHOGEN, XANTHOMONAS-ALBILINEANS, USING TISSUE BLOT IMMUNOASSAY, ELISA, AND ISOLATION TECHNIQUES

Tissue blot immunoassay, ELISA, and isolation techniques were compared for detection of Xanthomonas albilineans in sugarcane tissues at different positions along the stalk. X. albilineans was detected in the highest frequency in samples from mature plants at the internode superior to 62.5% of the total internodes. This tissue position had the highest frequency of detection and the highest optical density readings with ELISA for both symptomatic and asymptomatic stalks. The number of infected vascular bundles was highest in samples taken from the upper half of symptomatic stalks. The frequency of detection from symptomatic stalks was 67.0, 90.4, and 98.9% for isolation, ELISA, and tissue blot immunoassay techniques, respectively. X. albilineans was detected by the same three techniques, respectively, in 26.6, 6.3, and 16.2% of the asymptomatic stalks taken from the same plots. The tissue blot immunoassay technique was 98.9% effective in detecting X. albilineans in symptomatic stalks, and both that assay and isolation techniques would be most useful in detecting latent infections in asymptomatic stalks.