Comparison between Serological and Molecular Detection of Citrus Canker Pathogen (<i>Xanthomonas axonopodis</i> pv. <i>citri</i>)

Abstract

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract The specificity and sensitivity of serological and molecular tools for the detection of citrus canker pathogen (Xanthomonas axonopodis pv. citri; Xac) were investigated and compared. Virulence Xac BP210 was used as antigen for antisera production. The sensitivity of 1:2,000 diluted antisera were at 10 6 CFU/mL for live cell and 10 5 CFU/mL for dead cells. The cross-reaction of the antisera was observed only with X. campestris pv. vesicatoria but not other Xanthomonas nor other unrelated bacteria tested. Molecular tool was performed using specific primer to the rpf gene on Xac. The PCR amplification indicated that, allXac isolates amplified a product of 581 bp which was not seen in other Xanthomonas sp. and unrelated bacteria tested. The sensitivity of these specific primers was down to at least 1 cell which was effective to detect the pathogen in both infected symptomatic and asymptomatic lime tissues. The serological tool was able to detect the pathogen only on infected leaves of day 4 post inoculation when the symptoms were already detected by eye. The serological tool can be used to detect and quantify the present of Xac to study the disease development on symptomatic tissues.