Detection of dsRNA in Particles of Vicia Cryptic Virus and in Vicia faba Tissues and Protoplasts

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Abstract
Isometric particles of vicia cryptic virus (VCV), purified from Vicia faba seedlings infected through seed, had a buoyant density in CsCl of 1.37 g/ml. Analysis by PAGE showed that VCV particles contained three species of dsRNA with mol. wt. of 1.37 × 106, 1.26 × 106 and 1.21 × 106. These dsRNA species were also detected in extracts from leaves, stems, roots, flowers, seeds and mesophyll protoplasts of V. faba; dsRNA was readily detected in extracts from one leaflet (about 0.6 g). Slower-migrating species of dsRNA occurred in many leaf extracts but were not obtained from VCV particles. Electrophoresis of dsRNA extracts in gels that are then stained with silver appears to be a simple and reliable method for detecting ‘cryptic’ viruses. Using this method, VCV dsRNA was detected in 18 cultivars of V. faba, but not in cultivars Beryl and Minica which were thought from previous work to be free from VCV. Neither VCV particles nor VCV dsRNA were detected in VCV-free individual V. faba plants inoculated with VCV mechanically or by dodder. VCV was not detected in leaves of plants affected by cytoplasmic male sterility or in a maintainer line for this condition.