First report of tobacco necrosis virus causing the ABC-disease on potato tubers in Bulgaria.

Potato (Solanum tuberosum) is a widely spread species and its cultivation is mainly concentrated in small to middle acreage (up to 5 ha) farms in Bulgaria. At the end of 2015, ABC-disease resembling symptoms (Noordam 1957) were found on freshly stored potato tubers in the region of Varna, in northeastern part of the country. About 5% of the tubers (cv. Melody) were damaged and possessed varying sized sections with (A) dark brown raised patches, (B) dark sunken lesions, and (C) light brown cracked patches. When a portion of symptomatic potato tubers was placed in a fridge at 3-4°C in darkness, the necrotic lesions became darker but no other or supplementary symptoms had developed after nine months storage. The ABC-disease and its pathogen tobacco necrosis virus (TNV) was found in Europe, firstly some decades ago in the Netherlands (Noordam 1957), then in Italy (Peters 1981), and most recently in Sweden (Beucha 2014). Symptomatic tubers were subjected to a DAS-ELISA screening using the RT-0070 antibody set ...