Archivio Journal of Plant Pathology

Abstract:

Bacterial wilt caused by Ralstonia solanacearum, is one of the most important diseases of potato in tropical, subtropical and warm temperate regions of the world and is prevalent in many areas in India. The disease was only once reported from Indore and Jabalpur in Madhya Pradesh (India) in 1970, but was never a problem until 2007. From 2007, the disease suddenly emerged as a major constraint for potato cultivation in this region causing heavy crop losses; hence, warranting immediate steps for its management as the region is known to produce potatoes mainly for processing. Therefore, surveys were conducted to know the exact status of bacterial wilt and brown rot of potato and to collect plant and tuber samples from infested fields in several villages of Indore, Ujjain and Devas districts of the Malwa region of Madhya Pradesh during December 2009 and February 2010. The disease incidence ranged from traces to 80% depending upon the seed source. Wherever the farmers used healthy, certified seed, incidence of bacterial wilt and brown rot was negligible or very low. The identity of 21 of 22 bacterial isolates from infected potato plant/tuber samples from Indore, Ujjain and Devas districts of Malwa region was confirmed as R. solanacearum by colony characteristics on Kelman’s TZC agar medium, PCR with R. solanacearum specific primers YII and OLI 1and a pathogenicity test on potato. Using biochemical tests, based on the ability to utilize disaccharides and oxidise hexose alcohols, 21 isolates were categorized as biovar 2 which were further identified as phylotype II sequevar 1 as the characteristic race 3 biovar 2 specific 278 bp band was amplified from their DNA using the primer pair 630/631. All the 21 isolates proved to be pathogenic on potato, 18 on tomato, 15 on eggplant but none on pepper. To the best of our knowledge, this is the first report of occurrence of R. solanacearum race 3 biovar 2, phylotype II sequevar 1 in the Madhya Pradesh state of India.