Further evidence of multiplication of sowthistle yellow vein virus in its aphid vector, Hyperomyzus lactucae

Abstract

Bacilliform particles, approximately 220 mμ long and 80 mμ wide, were found associated with the nuclei of cells of sowthistle, Sonchus oleraceus, infected with the sowthistle yellow vein virus (SYVV). Similar particles were found within the nuclei of cells of the salivary tissue of aphid vectors, Hyperomyzus lactucae, that had been reared on virus-infected plants. Leaf dip preparations from diseased plants, negatively stained with sodium phosphotungstate, had similar particles, but the majority were bullet-shaped rather than bacilliform. Particles were also found in plant extracts that had been concentrated by ultracentrifugation, but particle distortion and disintegration increased with this procedure. Aphids injected with such centrifuged extracts transmitted the virus, after a latent period of 8–10 days, to healthy sowthistle seedlings. The nuclear infection in the aphid is interpreted as additional evidence that SYVV multiplies in the vector, and the results are discussed in conjunction with lettuce necrotic yellows and other bacilliform viruses from plants and animals.