Figure 8.

Hyperaccumulation of Rx in the Nucleus Causes Loss of Resistance to PVX.

The indicated constructs were transiently expressed in transgenic N. benthamiana:Rx4HA (top and middle panels) or transiently coexpressed with Rx-4HA (from a binary vector) in wild-type N. benthamiana (bottom panel) in the marked areas on one leaf. Simultaneously, PVX or PVX-GFP inoculation was performed by coinfiltrating a dilute suspension of agrobacterium carrying a binary vector encoding infectious PVX or PVX-GFP. The appearance of spot lesions (Rx-mediated trailing HR) visible under daylight and GFP foci visible under UV light indicate partial loss of resistance. To be able to study both compromised and enhanced resistance, Rx-4HA was expressed transiently in wild-type N. benthamiana (bottom panel), where the induced resistance was to a certain extent already partial in the negative control (GUS). At 6 or 7 d after inoculation (dpi), leaves were photographed under daylight (first row of panels) or UV light (third row of middle and bottom panels), the latter to visualize the GFP fluorescent foci. After that, chlorophyll was removed and leaves were photographed under daylight to visualize the spot lesions (second row of panels).