Biochemical and molecular detection of Xanthomonas citri subsp. malvacearum,the causal organism of bacterial blight of cotton in the northern cotton zone of Nigeria

Xanthomonas citri subsp. malvacearum causes severe qualitative and quantitative losses to farmers in cotton growing areas of the world. Timely detection of the bacterial pathogen causing blight in cotton is extremely important in developing management strategies against the disease. Bacterial isolates were extracted from cotton seeds obtained from five ginneries located in northern Nigeria. Bacterial colonies were isolated and tested for nitrate reductase activity, oxidase reaction, catalase reaction, aesculin hydrolysis, utilisation of carbon from different sources and Tween 80 hydrolysis was assessed, PCR was also carried out on the isolates. The studied bacteria from the four locations reacted positively to Tween 80 hydrolysis and catalase test. Maltose digestion was negative in all samples, hydrolysis and digestion of arabinose, arabitol, cellobiose, lactate and acetate were positive. They were thus identified as members of the species X. citri based on the biochemical tests run. Molecular detection using PCR positively identified the pathogen.