COMPARATIVE BIOCHEMICAL ASSESSMENT OF THE COTTON BACTERIAL BLIGHT PATHOGEN

Abstract

Bacterial blight, caused by Xanthomonas citri pv. malvacearum (Xcm), is a significant disease impacting cotton production in Pakistan. Effective disease management relies on a comprehensive understanding of the pathogen’s characteristics. In this study, Xcm was isolated from infected cotton samples collected in the Bahawalpur region and subsequently purified. Identification was carried out using morphological, biochemical, and cultural analyses.

Biochemical testing indicated that the isolates were positive for potassium hydroxide (KOH), catalase, oxidative-fermentative (OF) test, urease, starch hydrolysis, citrate utilization, methyl red, Voges-Proskauer, and casein hydrolysis, while they were negative for Gram staining, indole production, and arginine dihydrolase activity. Cultural characterization revealed mucoid, convex colonies with yellow to orange pigmentation on nutrient agar, and flattened or slightly raised mucoid colonies ranging from bright to pale yellow on yeast extract dextrose calcium carbonate (YDCA) agar.

These findings provide critical insights for researchers, aiding in the accurate identification of Xcm and supporting in vitro evaluation of potential strategies to control bacterial blight in cotton.