C aulimoviridae (Plant Pararetroviruses)

Abstract

Family Caulimoviridae comprises eight genera of plant viruses whose members replicate by reverse transcription and whose virions contain double‐stranded deoxyribonucleic acid. In a recent survey of the international scientific community, Cauliflower mosaic virus (CaMV), the type species of the family, was ranked sixth in the world in a list of the most scientifically or economically important plant viruses. This notoriety is due purely to the major conceptual advances that have been made in plant virology using CaMV as a model pathogen. However, several relatively lesser known viruses in the family, such as rice tungro bacilliform virus and the cacao swollen shoot virus species complex, are very serious constraints to crop production in tropical regions of the world. In this article, information on the taxonomy, replication cycle, vector transmission, epidemiology and disease management of this important group of plant viruses is summarised. Key Concepts The Caulimoviridae is the only family of plant viruses with a double‐stranded deoxyribonucleic acid (dsDNA) genome, and in common with all viral retroelements, incorporates a reverse transcription step in the replication cycle. Cauliflower mosaic virus is the type species of the family and has been a very important model plant virus for elucidating fundamental aspects of virus replication, cell‐to‐cell movement and aphid transmission. Members of the Caulimoviridae are most prominent in tropical regions, where they cause serious diseases such as rice tungro, cacao swollen shoot and banana streak disease. The most important component of a control programme for these viruses is to reduced inoculum levels by using clean planting material, avoiding overlapping crops, and removing diseased plants and alternative hosts of the virus. In some host species, infection can arise as a consequence of activation of viral DNA that is integrated into the nuclear genome of the plant.