SURVEILLANCE OF RALSTONIA SOLANACEARUM INFECTING POTATO CROP IN PUNJAB

Abstract

Potato is the most consumed vegetable in Pakistan and is regarded as source of food and energy for millions of people around the world. Bacterial wilt of potato caused by Ralstonia solanacearum is an important disease causing huge losses worldwide. Punjab is the major potato producing province in Pakistan contributing 80% production. This study was conducted to record the incidence and severity of bacterial wilt disease in Pakistan's major potato growing areas of Punjab and also to characterize the pathogen. Survey of several fields from each area viz; Lahore, Okara, Faisalabad, Sahiwal, Sialkot and Taxila was done for the collection of samples of plants and soil. R. solanacearum was isolated on Triphenyl-tetrazolium chloride (TTC) agar media from infected samples followed by pathogenicity tests on potato plants. Race of the isolates of R. solanacearum was determined and the isolates were characterized biochemically and identified on molecular basis using the R. solanacearum-specific primer pair 759/760 which amplified 280 bp fragment of DNA. Data obtained from the survey of potato growing areas revealed bacterial wilt as a common problem. The highest incidence of bacterial wilt (24.4%) was observed in Okara. Areas including Sahiwal, Lahore, Faisalabad, Sialkot and Taxila were having 21.7, 18.0, 23.2, 19.8 and 8.5 percent incidence respectively while disease prevalence was 100% in all areas except Taxila (60%). The isolation from the infected samples was done and the isolates were determined to be belonging to race 3 biovar 2. According to the molecular identification tools, 21 isolates were confirmed to be R. solanacearum.