Figure 6.

The overexpression of luminal binding protein (BiP) attenuates the cell death induced by P25/helper component‐proteinase (HC‐Pro). (A) Nicotiana benthamiana leaves were infiltrated with combinations of Agrobacterium cultures expressing T7‐tagged P25, HC‐Pro, BiP or green fluorescent protein (GFP), as indicated. Leaf discs were excised and assayed for electrolyte leakage at 8 days post‐infiltration (dpi). Data represent the means ± standard errors of six replicates, each consisting of four plants that received the same treatment. Statistically significant differences between means were determined by employing Scheffé’s multiple range test. Different letters indicate significant differences at P < 0.05. (B) Leaves were stained with 3,3′‐diaminobenzidine (DAB) solution at 8 dpi. (C) Western blot analyses of extracts derived from leaf patches at 8 dpi, using antibodies against the T7 (top panel) or haemagglutinin (middle panel) epitope. 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 BiP bands, normalized for the loading controls, were quantified by densitometric analyses. (D) Effect of BiP expression on P25 + HC‐Pro‐induced membrane modification in transgenic N. benthamiana plants expressing endoplasmic reticulum (ER)‐GFP (line 16c). GUS, β‐glucuronidase. Photographs were taken at 6 dpi. Bars in each panel represent 20 µm. [Colour figure can be viewed at wileyonlinelibrary.com]