FORMATION AND EVOLUTION OF TOMBUSVIRUS DEFECTIVE INTERFERING RNAS

Defective interfering (DI) RNAs associated with members of the genus T ombusvirus are among the most extensively characterized. These molecul es, which represent replicable deletion mutants of viral genomes, are able to accumulate to high levels in viral infections and have the eff ect of suppressing virus accumulation and attenuating virus-induced sy mptoms in host plants. Numerous studies have led to a greater understa nding of how these molecules are formed and what factors influence the ir accumulation. Here an overview is provided of what is currently kno wn about the structure, formation and evolution of this important clas s of sub-viral replicon. (C) 1996 Academic Press Ltd.