Through isolation of the affected genes in these mutants, the host factors that govern susceptibility or resistance to viruses can be identified. Plants that carry functional RTM1 and RTM2 genes are resistant. The function of these genes in virus restriction is currently under study. Like animal viruses, plant viruses have evolved mechanisms to suppress host defense responses. This defense mechanism may occur during most viruses infections and may limit the extent of virus accumulation.
Several viruses encode suppressor of gene silencing.
This protein functions to arrest gene silencing and permit prolonged replication and systemic movement of TEV throughout the host. Cell 95, 461-470. Selectable viruses and altered susceptibility mutants in Arabidopsis thaliana. USA 96, 772-777. Cloning of the Arabidopsis RTM1 gene, which controls restriction of long-distance movement of tobacco etch virus.