Double-Stranded RNA-Viruses; Wound Tumor Viruses

The genome of wound tumor viruses (WTV) consists of 12 double-stranded RNA segments. Neither of them is infectious. The wound tumor viruses of plants and animals (reoviruses) are related and are characterized by a number of common activities. They contain, for example, the enzyme transcriptase that transcribes single-stranded RNA or, in other words, produces an mRNA complementary to the transcribed strand. Each of the 12 segments can be transcribed and it is assumed that each of them encodes one protein. Replication occurs within the cytoplasm. Infection takes place via insects (e.g. aphids) that function both as a vector and an intermediate host, i.e. the virus multiplies in their tissue, too.

More than 50 plant species are known to be susceptible for wound tumor viruses. Among the symptoms are small tumors at the stem and larger and more numerous ones at the roots. WTV-induced wound tumors of leguminosae can be clearly distinguished from the nodules caused by nodule bacteria. In some plant species, like the lobelia, the infection induces the development of organs from otherwise normal organs, e.g. a leaf can develop at the lower leaf surface of another leaf.