Use of PCR as a tool for diagnosis of tobacco rattle tobravirus in seed potatoes

Diagnosis of tobacco rattle tobravirus (TRV) in potato is difficult because of the existence of non-encapsidated NM-type strains, because similar symptoms are caused by potato mop-top furovirus and physiological internal rust spot and because serological tests are inefficient. The aim of this study was first to compare ELISA and PCR tests. The former was found to be ineffective, so only the PCR technique was in a survey of numerous seed-potato lots (200-tuber samples) from different EU countries. A large disparity was found according to geographical origin, with infection levels of German, Dutch and French seed potatoes of 10.3, 8.5 and 0.6%, respectively. There is a real risk that planting tubers with such infection levels will newly contaminate soil. Besides, TRV is not considered in the EU texts on marketing of seed potatoes, so there is no legal recourse if seed-potato lots are found to be TRV-infected.