Identification and characterization of peanut stunt cucumovirus from naturally infected alfalfa in Iran

A mechanically transmissible virus was isolated from a naturally infected alfalfa plant (Medicago satira) in Karaj, Iran. It induced fern-leaf symptoms in Lycopersicon esculentum, general chlorosis and stunting in Arachis hypogoea, local lesions and systemic infection in Chenopodium quinoa, Phaseolus vulgaris and Vigna unguiculata but only local lesions in C. amaranticolor. In gel-immunodiffusion tests, it reacted strongly with an antiserum to peanut stunt cucumovirus (PSV), moderately with two of six antisera to cucumber mosaic cucumovirus (CMV) and with two of five antisera to tomato aspermy cucumovirus. Its spherical virions (28 nm in diameter) contained a coat protein of approximately 29 kDa and encapsidated four species of RNAs with similar electrophoretic mobilities to RNAs 1-4 of CMV strains Fny and LS and those of PSV strains J and W. Its encapsidated RNAs hybridized in slot-blot hybridization assay with the complementary DNA probe of PSV-W RNAs but not with those of CMV strains. Therefore, on the basis of biological, serological and physico-biochemical properties, the virus was identified as PSV. No satellite RNA was associated with the virus. This is the first report of PSV in Iran.