Detection and elimination of viruses infecting sweet potatoes in Hungary

Sweet potato has been grown in Hungary for the last three decades, and its popularity is increasing among farmers and consumers. Its production is hampered by pests and diseases due to poor agricultural practices, such as the use of virus-infected propagation materials. We tested the presence of 15 viruses by PCR and quantitative PCR in 110 sweet potato plants collected from seven regions in Hungary. Seven viruses in single or multiple infections associated with a wide range of foliar symptoms were detected: sweet potato chlorotic stunt virus (SPCSV), sweet potato virus G (SPVG), sweet potato virus C (SPVC), sweet potato feathery mottle virus (SPFMV), sweet potato virus 2 (SPV2), sweet potato leaf curl virus (SPLCV), and sweet potato pakakuy virus (SPPV). This is the first report on the occurrence of the begomovirus SPLCV in sweet potatoes in Hungary. The infectivity and identity of these viruses were confirmed through bioassays (grafting to Ipomoea setosa) and sequencing of the PCR-amplified sections of their genomes, respectively. Due to the necessity for virus-free sweet potato propagation material in Hungary, virus elimination was carried out successfully in five out of six genotypes important for Hungarian farmers using heat treatment and meristem tip culture. All five viruses detected in the plants before heat treatment were removed except SPPV, which persists after heat treatment. Production and strict regulation of virus-free sweet potato propagation materials are recommended to avoid exacerbating the virus situation and protect Hungarian farmers from further losses.