SUSCEPTIBILITY AND RESISTANCE OF ARABIDOPSIS-THALIANA TO TURNIP CRINKLE VIRUS

The Arabidopsis thaliana ecotype Dijon (Di-0) is resistant to turnip crinkle virus (TCV). It exhibited either no symptoms 3 wk after inoculation or mild symptoms such as stunting, curled bolts, and seliques and early desiccation. Twenty-two other ecotypes of A. thaliana developed a lethal systemic necrosis within 3 wk of inoculation with TCV. Five days after inoculation, TCV genomic RNA accumulated in Di-0 plants, grown under different environmental conditions, at less than 1% of the level found in the susceptible ecotype Col-0. To monitor the accumulation of viral RNA in both inoculated and uninoculated leaves of Col-0 and Di-0, virus-specific probes were hybridized directly to the RNA within whole plants. Results using this procedure revealed that in Col-0 the virus had spread throughout the vascular tissue by 7 days postinoculation. In Di-0, signal was detected mainly in the inoculated leaf and in the opposite leaf of the same age. Di-0 protoplasts, however, were found to support virus replication. These results suggest that restricted virus spread, and not a block in virus replication, is responsible for the resistance of Di-0 to TCV.