First Report of Pepino mosaic virus on Natural Hosts

Pepino mosaic virus (PepMV) is a potexvirus recently identified as the causal agent of a new disease occurring in protected tomato (Lycopersicon esculentum Mill.) crops in the Netherlands (2). PepMV has been subsequently identified in England, Germany, Italy, Morocco, Portugal, and Spain. The new disease has become a serious problem for tomato production in Europe. Most infected tomato plants expressed leaf distortion, chlorosis, and yellow mosaic. Other plants expressed mosaic and bubbling of the leaf surface. Tomato fruits showing severe discoloration and mosaic were observed in protected tomato crops. Symptoms attenuated in tomato plants as the ambient temperature increased. At present, only Solanum muricatum Ait. (Peruvian pepino) and L. esculentum are affected by PepMV.To determine possible reservoir hosts for this virus, 70 samples from Amaranthus sp., A. viridis (L.) Britton et al., Chenopodium murale L., Convolvulus arvensis L., Malva parviflora L., Nicotiana glauca Grah., Polypogon monspeliensis (L.) Desf., Senecio vulgaris L., Sisybrium sp., Solanum nigrum L., and Sonchus oleraceus L. were analyzed. The plants were collected around greenhouses affected by PepMV from different regions in Spain (Murcia and Canary Islands). The samples were analyzed for PepMV by double-antibody sandwich enzyme-linked immunosorbent assay with a commercial antiserum (DSMZ AS-0554, Biologische Bundesantstal, Braunschweig, Germany). Only Amaranthus sp., M. parviflora, N. glauca, Solanum nigrum, and Sonchus oleraceus tested postive. The presence of PepMV in these weed species was confirmed by electron microscopy and reverse transcription-polymerase chain reaction using degenerate primers for potexvirus (1). All the hosts analyzed were asymptomatic. However, symptoms were reproduced by mechanically inoculating tomato plants with sap from naturally infected weeds. To our knowledge, this is the first report of natural infection of weeds by PepMV. References: (1) A. Gibbs et al. J. Virol. Methods 74:67, 1998. (2) R. A. A. Van der Vlugt et al. Plant Dis. 84:103, 2000.