Preliminary observations on the possible soilborne transmission of closterovirus-like particles

A survey was carried out to check the possible infectivity of soil samples collected from fields where crops were grown which revealed infections by non soilborne viruses. These samples were previously checked to exclude the presence of fungi and/or nematodes known to be virus vectors. Then, they were analyzed either by treatment with 0.01M Tris-HCl buffer, pH 7.6, to attempt the extraction of virus particles, or checking the effects on bait plants. One of this samples, in which tomato seedlings were previously transplanted, after this trial, in presence of tomato roots and other vegetation debris, was mixed with sterile peat and used for transplanting as bait plants Nicotiana benthamiana, N. occidentalis and again tomato. These three hosts revealed presence of viral particles with ultrastructural characteristics typical of closterovirus-like particles. Similar particles were extracted directly from the soil