Figure 3.

Disruption of endoplasmic reticulum (ER) correlates with the silencing suppression activity of P25. (A) Transgenic Nicotiana benthamiana plants expressing ER‐GFP (green fluorescent protein) (line 16c) were infiltrated with Agrobacterium cultures expressing T7‐tagged P25, helper component‐proteinase (HC‐Pro) or β‐glucuronidase (GUS) alone or a combination of cultures expressing HC‐Pro plus T7‐tagged versions of either P25wt or P25 A104V, T117A, K124E mutants, as indicated. Large irregular inclusions are marked by arrows. Photographs were taken at 8 days post‐infiltration. Bars in each panel represent 45 µm. (B) Western blot analyses of extracts derived from leaf patches at 8 dpi, using antibodies against the T7 epitope (top panel) or Plum pox virus (PPV) HC‐Pro (middle panel). The lower panel below the western blots shows the Ponceau S‐stained membrane after blotting, as a loading control. The intensities of the P25 and HC‐Pro bands, normalized for the loading controls, were quantified by densitometric analyses. [Colour figure can be viewed at wileyonlinelibrary.com]