Host suppressors in Arabidopsis thaliana of mutations in the movement protein gene of Cauliflower mosaic virus

A novel genetic screen was used to identify host factors in Arabidopsis tha liana that suppress mutations in the Cauliflower mosaic virus (CaMV) moveme nt protein gene (gene I). A series of small mutations was made in gene I an d the mutations were tested for their suitability in a suppressor screen. T he first round of screening yielded only revertants or second-site mutation s in gene I. A derivative of one of the second-site mutant viruses (N7) tha t was delayed in symptom production was used in a second round of screening for suppressor plants that accelerated symptom production. Two candidate s uppressor plants were found that accelerated by 1 to 4 days the first appea rance of symptoms caused by the mutant viruses. One of the suppressors (5-2 ), called asci acceleration of symptoms by CaMV N7), was mapped to chromoso me Two additional loci that differentially affect N7 virus susceptibility i n the parental Columbia and Ler ecotypes were mapped to chromosomes 3 and 4 by quantitative trait locus (QTL) analysis.