Water samples were collected from irrigation ditches and drainage canals surrounding fields in southern Greater Poland. Initially, the samples were subjected to low and highspeed centrifugation and obtained pellets were used to perform biological assays. Viral identification involved biological, electron microscopic as well as molecular methods. The occurrence of Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV) was demonstrated in 12 of the 17 examined water sources. The molecular analysis results showed TMV and ToMV co-infections in the analysed water samples. To our knowledge, this is the first report of tobamoviruses being found in environmental water in Poland.
Plant viruses create many changes in the morphology of the plant cell once the infection process has begun. This paper describes and compares the ultrastructural changes induced in maize cells by two isolates of Maize dwarfmosaic virus (MDMV), Spanish (MDMV-Sp) and Polish (MDMV-P), and one isolate of Sugarcane mosaic virus (SCMV) at 10 and 42 days post-inoculation: the concentration and arrangement of virus particles, inclusion bodies associated with infection, and other cytological alterations. The most important difference between maize cells infected with MDMV isolates and with SCMV-P1 was in the form of cytoplasmic cylindrical inclusions. In cells infected with MDMV only typical inclusions such as pinwheels and scrolls were observed, but laminar aggregates were also present in SCMV-infected cells. No virus particles were found in plant cell organelles. Specific virion arrangements occurred in cells infected with MDMV-Sp and SCMV. The most interesting new finding was of specific amorphous inclusions in the cytoplasm of MDMV-Sp-infected cells, which clearly differentiated the two MDMV isolates studied.