CHARACTERIZATION AND VECTOR RELATION OF A SEROLOGICALLY DISTINCT ISOLATE OF TOBACCO RATTLE TOBRAVIRUS (TRV) TRANSMITTED BY TRICHODORUS-SIMILIS IN NORTHERN GREECE

A virus isolated from diseased tobacco plants growing in Macedonia, no rthern Greece, had host range and physicochemical properties typical o f a tobravirus. Although it was serologically unrelated to any of the ten tobravirus isolates tested, it reacted in spot hybridization tests with a probe derived from RNA-1 of tobacco rattle virus (TRV) strain SYM. Therefore, the isolate probably represents a previously undescrib ed serotype of TRV. Male, female and juvenile Trichodorus similis nema todes recovered from the rhizosphere of the diseased tobacco plants tr ansmitted TRV in each of three laboratory experiments. In two of these experiments 50% and 54%, respectively, of the nematodes transmitted v irus to Petunia hybrida bait plants, whereas only 18% transmitted viru s to Nicotiana tabacum plants in a third test. Ultrathin sections of t he feeding apparatus of individual nematodes, which had transmitted vi rus, were examined by electron microscopy. Virus particles were observ ed, retained as a monolayer in the apices of the oesophageal lumen and as a group of particles within a matrix in the open part of the lumen .