Fig. 3From: Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana The effects of MtRDR1 expression and SA treatment on the recovery of N. benthamiana plants from TMV-induced plant death. a Five-week-old transgenic control (plants transformed with an ‘empty’ transformation vector: EV-control) and MtRDR1-transgenic (MtRDR1) plants were pre-treated with a solution of 1 mM SA in 0.05 % (v/v) ethanol (+SA) or a 0.05 % (v/v) ethanol control solution prior to inoculation with TMV U1. Plants were monitored over a 5-week period and the number of plants killed by the virus recorded. With the transgenic control plant group, TMV U1 had killed all plants within 31 days of inoculation. Pre-treatment with 1 mM SA delayed plant death by a few days but did not prevent it. TMV U1-induced plant death was suppressed in all the MtRDR1-expressing N. benthamiana plants, regardless of whether they were treated with water or with SA. b Symptoms at 75 days post-inoculation with TMV U1 in transgenic control and MtRDR1-transgenic N. benthamiana plants. MtRDR1-transgenic plants pre-treated with SA (+) or treated with control solution (-) recovered but SA-treated plant growth was more vigorous (scale bar = 8 cm). Data and photographs are from one experiment, out of a total of four independent experiments. c Western blot analysis of TMV using anti-TMV coat protein (TMV CP) serum shows that TMV was present in the newly emerged, green leaf tissue in recovering MtRDR1-transgenic plants treated with SA (+) or control solution (-). Leaf samples taken at 75 days post-inoculation or mock-inoculation (each lane is loaded with protein extracted from one plant). Equal loading was confirmed by Ponceau S staining of the western blot membrane with the position of the ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (LSU) indicatedBack to article page