Genetic polymorphism in Indian strains of Xanthomonas campestris pv. mangiferaeindicae, mango bacterial canker disease pathogen

Bacterial canker (black spot) incited by Xanthomonas campestris pv. mangiferaeindicae (Xcmi) is an endemic problem in the major mango-growing regions, especially in the area where harvesting coincided with rains. The aim of this study was to characterize Xcmi by molecular approaches. Genetic variations in strains of Xcmi were observed and measured using hrp gene RFLP, RAPD and Rep-PCR. Results of present investigation confirm the presence of diversity within Xcmi strains. It is interesting to note that the Rep-PCR technique to be extremely reliable, reproducible, rapid and highly discriminatory in the study of diversity in case of Xcmi. The reliable identification of the mango bacterial canker pathogen by DNA amplification of hrp gene will greatly facilitate disease diagnosis, which leads to its successful management. This can also be used for ecological and epidemiological studies. Further, the use of oligonucleotide primers for the hrp gene cluster region provides certainty for identification of strains of X. campestris that may not be possible with other methods.