involved in infection. Some groundnut varieties that are resistant to rosette disease have been demonstrated to be highly resistant to GRV and its satellite RNA but fully susceptible to GRAV. Transmission The main vector for groundnut rosette virus is the groundnut aphid (Aphis craccivora). When it sucks the sap of an infected plant it receives groundnut rosette virus and satellite RNA, packaged together within a coating of groundnut rosette assistor virus. The disease is epidemic in nature and there is a seasonal cycle of infection, but the origins of this virus are unknown. In Africa, the groundnut aphid feeds on as many as 142 different species of plant, many of them in the family Fabaceae, and the groundnut rosette virus is presumed to have originated among these. Research has shown that although other host plants exist for GRV, GRAV and satellite RNA individually, the only known natural host plant for all parts of the complex is the groundnut. Virus resistant varieties of groundnut have been discovered but mostly have a long growing period (five to six months rather than three to four for other varieties) and may therefore be more susceptible to drought. A breeding programme has been established in Malawi focussing on disease resistance, early maturity and high yield. References External links Family Groups—The Baltimore Method Umbraviruses Viral plant pathogens and diseases Peanut diseases