Molecular characterization of Xanthomonas axonopodis pv. vignaeradiatae, causing bacterial leaf spot of green gram
Keywords:Bacterial leaf spot, DNA, genetic diversity, green gram, pathogenicity, random amplified polymorphic DNA
AbstractXanthomonas axonopodis pv. vignaeradiatae causes bacterial leaf spot of green gram, an industriallyÂ important legume. Ten isolates of X. axonopodis pv. vignaeradiatae, obtained from green gram fields ofÂ Udaipur district, Rajasthan were identified at the pathovar level using virulence trials on the susceptibleÂ green gram genotype (SML 668), which confirmed their phytopathogenic specialization on green gram.Â Polymerase chain reaction (PCR)-based techniques such as, random amplified polymorphic DNAÂ (RAPD)â€“PCR was successfully employed to elucidate the pathogen population structure and intraÂ pathovar relationship among a set of ten X. axonopodis pv. vignaeradiatae isolates. There was a significantÂ variation in their pathogenicity and genetic structure. The pathogenicity data were found to be in line withÂ the molecular data to some extent. RAPD markers revealed a high level of genetic diversity across theÂ isolates employed in comparison. There was no correlation between DNA amplification product patternsÂ and geographic sites of isolation, suggesting that this bacterium has spread largely through exchange ofÂ infected plant germplasm. This is the first report on the molecular characterization of X. axonopodis pv.Â vignaeradiatae isolates from Rajasthan, India.
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