Infection of Colletotrichum acutatum and Phytophthora infestans by taxonomically different plant viruses

Viruses are common in fungi and oomycetes and some of these viruses share sequence identities with plant viruses belonging to different families and genera. Replication of the plant virus tobacco mosaic virus has been demonstrated in the phytopathogenic fungi Colletotrichum acutatum, C. clavatum and C. theobromicola and more recently, infection of cucumber mosaic virus has been reported in Rhizoctonia solani isolated from potato plants in the field. Here we show that artichoke mottled crinkle virus, potato virus X, potato virus Y and cucumber mosaic virus plus its satellite RNA can replicate and persist in C. acutatum at least through the first subculture and that artichoke Italian latent virus, artichoke mottled crinkle virus, potato virus X, potato virus Y, tobacco mosaic virus and cucumber mosaic virus plus its satellite RNA can replicate and persist in Phytophthora infestans at least through the first subculture. These observations suggest that, unlike in plants, there may be a different basis for host-virus specificity in plant virus infection in filamentous fungi and oomycetes

Effect of Diaporthe RNA virus 1 (DRV1) on growth and pathogenicity of different Diaporthe species

A 4.1 kbp positive-strand RNA virus known as Diaporthe RNA virus 1 (DRV1) occurs in hypovirulent, non-sporulating isolates of the fungal pathogen Diaporthe perjuncta. A full-length cDNA clone of DRV1 was developed and RNA transcribed from the cDNA clone used to transfect different Diaporthe spp. The transfected species included three D. ambigua isolates and an unidentified Phomopsis asexual state of a Diaporthe sp. Successful transfections were confirmed using RT-PCR. Although the in vitro-transcribed positive sense single-stranded RNA used for transfection included vector sequences at both ends, the genomes of progeny virus from DRV1-transfected isolates were free of the vector sequences. Transfection resulted in morphological changes in these fungal pathogens. However, the presence of DRV1 did not reduce growth rate in two of the three D. ambigua or the Phomopsis sp. significantly. Pathogenicity studies showed that the transfected isolates have reduced aggresiveness