Detection of potato virus s (PVS) by serological and RT-PCR methods in Khorasan Razavi and Hamedan Provinces

Potato virus S is a member of the genus Carlavirus in the family of Flexiviridae, with curved filamentous particles 650×12 nm and positive single stranded RNA genome. This virus is one of the most common viruses that infected all of potato varieties in the world. Susceptible host species belong mainly to the families Solanaceae, Chenopodiaceae and Amaranthaceae. Potato virus S transmits by mechanical inoculation and Myzus persicae as well in a non-persistent manner. Samples of 555 tubers showing symptoms of mosaic, necrotic spots, vein partial deepening, rugosity, undulation of the margin, wilting and dwarfing from 50 fields in Khorasan Razavi and Hamedan provinces were collected. After tubers passed dormancy period at 4˚C and germinated, PVS polyclonal and special antiserum were used in DAS-ELISA to identify infected potato tubers. Sap of infected samples inoculated on indicator plants such as Chenopodium quinoa and C. amaranticolor (chlorotic spots on the leaf), Nicotiana debneyi (severe mosaic), N. tabacum var. xanthi (immune) and Lycopersicon esculentum (mosaic). Results of ELISA test indicated that 69 samples out of 555 samples were infected. To confirm the results of ELISA test, RT-PCR and specific primer for amplification of coat protein gene were used. Specific primers amplified 1118 bp fragment related to coat protein of the virus.