Characterizing diversity of Dickeya zeae causing bacterial stalk rot of maize based on biochemical assays and antibiotic sensitivity
Maize growing areas of Punjab were surveyed during Kharif 2012 and 2013 for the occurrence of stalk rot disease. A total of sixty two isolates were collected, isolated and identified as off white colonies appearing on King's B medium. The isolates showed variation in virulence when tested on susceptible cv. Punjab Sweet Corn 1 and were grouped as highly virulent, moderately virulent and less virulent. All the isolates produced cavities on crystal violet pectate medium. A panel of 27 biochemical tests were used to characterize these isolates which showed differential reaction for utilization of starch and other carbohydrates, gelatin liquefication and growth at high salt concentration. Multiple antibiotic resistance was observed in all the isolates tested. Numerical analysis of phenotypic features revealed two major groups of isolates associated at 60 per cent similarity coefficient.