The occurrence of strawberry viruses and phytoplasmas in the Czech Republic.

摘要

Several symptoms of strawberry mottle, crinkle, vein banding, mild yellow edge as well of mixed virus infection were observed on Fragaria vesca clones after leaf graft bioassay. Isometric virus-like particles ranging from 21 to 50 nm in diameter, slightly flexuous filamentous particles (12 x 600-1200 nm), rhabdovirus-like virions (45-60 x 285-320 nm) and virus-like inclusions were observed by electron microscopy in several strawberry preparations. Dot blot hybridization and PCR analyses confirmed the presence of strawberry vein banding virus (SVBV) in several samples. Moreover, DNA was isolated from this material, amplified, sequenced, and it was found that the fragment from the middle part of the coat protein gene of the Czech SVBV isolates was nearly identical with the corresponding region of the American SVBV isolate. Isolates of Arabis mosaic virus, strawberry latent ringspot virus and tobacco necrosis virus D strain were mechanically transmitted from strawberries to differential host plants,purified, characterized by electron microscopy and antisera against them were prepared. Phytoplasmas belonging to aster yellows group (16SrI) subgroup I-C were detected in many strawberry plants which showed different types of symptoms: green petals, flower phyllody and early leaf reddening with subsequent decline. Electron microscopic observation of ultrathin sections confirmed the presence of phytoplasma structures in phloem tissues of diseased plants.