Inhibition of poly(I:C)-induced callose deposition by MPs of different viruses. A) Different MPs are functional. Unlike free RFP, RFP fusions to the MPs of TMV (MP^TMV:RFP), ORMV (MP^ORMV:RFP), and TVCV (MP^TVCV:RFP) complement the movement function of MP-deficient TMVΔM-GFP in N. benthamiana. Leaves were coinfiltrated with agrobacteria containing the respective RFP or MP:RFP-encoding plasmids together with highly diluted agrobacteria (OD_{600 nm} = 1 × 10⁻⁵) for agro-inoculation with TMVΔMPΔCP-GFP. Pictures were taken at 5 dpi. Scale bar, 1 cm. B) MP^TMV:RFP, MP^ORMV:RFP, and MP^TVCV:RFP localize to PD as shown by the presence of callose. MP-expressing leaves were stained with aniline blue and imaged after 30 min. Inlay images show magnifications of image areas framed by a dashed line. Scale bar, 20 µm. C and D) Expression of either MP^TMV:RFP, MP^ORMV:RFP, or MP^TVCV:RFP strongly reduces the induction of PD callose deposition in the presence of poly(I:C). Leaf disks excised from the RFP (control) or MP:RFP-expressing leaves 48 h after agroinfiltration were incubated for 1 d in water, then transferred into aniline blue solution with and without 0.5 µg/µL poly(I:C) and imaged after 30 min. C) Mean callose content in PD of poly(I:C)-treated and control-treated tissue. For each treatment, several leaf disks from 3 plants were analyzed for PD-associated callose levels. RFP data are combined data from the leaf disks that were used as RFP control in the individual agroinfiltration experiments. The total number of evaluated PD is given at the base of each column. Error bars show the Sem. One-way ANOVA of the mean values (P = <0.0001) followed by Sidak's test for pairwise comparisons. D) Relative increase in median PD callose deposition in poly(I:C)-treated tissue as compared to control-treated tissue (%) in the presence of the different RFP-fused MPs or RFP as control. ****P = < 0.0001; ns = nonsignificant.