Genetic Variability within Xanthomonas axonopodis pv. punicae, Causative Agent of Oily Spot Disease of Pomegranate

Bacterial blight is one of the most devastating diseases of pomegranate in India. It is known to be caused by the strains of Xanthomonas axonopodis pv. punicae (xap). As the control of disease varies with the use of pesticide agents, it becomes imperative to study the genetic variation among the pathogenic strains. Thirty-six strains of Xanthomonas axonopodis pv. punicae, were isolated from the diseased fruits of 3 varieties of pomegranate originating from 3 different provinces of Maharashtra, India. All the strains characterized phenotypically and genotypically were found to have diversity. The genetic diversity among the 36 Xanthomonas isolates was assessed using RAPD based techniques. A cluster dendrogram based on the random amplified polymorphic DNA (RAPD) showed that genetic diversity existed among the isolates of Xanthomonas. The genomic variation was found to be in the range of 0.55% to 0.95% among the isolates. The cluster analysis based upon band patterns formed two major clusters with 4 sub-groups. It can be concluded that this variability was genetic in nature irrespective of their location and the variety of pomegranate.