ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF XANTHOMONAS AXONOPODIS PV. CITRI FROM SELECTED SPECIES

Citrus fruits, that belong to the Rutaceae. family, have a great economic, nutritional, and therapeutic importance. It has long been a significant source of foreign exchange for Pakistan. Unfortunately, various diseases affect its production and quality, the deadliest of which is known as citrus canker caused by Xanthomonas axonopodis pv. citri. The goal of current research was to isolate and characterize the strains causing citrus canker on the basis of phenotypical and genotypical features. Fruits with possible canker lesions were used for the isolation from the different Citrus Orchards in Khanpur, District Haripur, Pakistan. Citrus fruits, both symptomatic and asymptomatic, were sampled and evaluated during the survey. Only diseased citrus fruits yielded Xanthomonas-like bacterial strains were isolated and identified by carrying out different biochemical tests including catalase, Kovac's oxidase and KOH test. The isolated strains were further identified through polymerase chain reaction (PCR) by using specific ITS primers. Total of eight bacterial isolates were identified to be Xanthomonas spp. through biochemical tests and molecular results revelled the 2A and 2B bacterial isolates as., Xanthomonas citri subsp. citri. (Xcc). Thus, it was concluded that isolated strains were pathogenic bacteria, that is an actual cause of bacterial canker in commercial citrus fruits. Our findings suggested that diseased citrus fruits, could act as a source of dispersal for citrus canker in areas like Pakistan.