Engineered nanomaterials suppress Turnip mosaic virus infection in tobacco (Nicotiana benthamiana)

Tobacco (Nicotiana benthamiana) and Turnip mosaic virus (TuMV) were used as a model system to investigate the potential of engineered nanomaterials (ENMs) for promoting crop growth and resistance to viral infection. A 5 mL ENM suspension of 50 or 200 mg L-1 consisting of either two metal-based nanoparticles (NP Fe2O3 or TiO2) or two carbon-based nanomaterials (NMs) (MWCNTs or C-60) was foliar-sprayed onto the leaf surface of tobacco daily for 21 days. Fully developed young leaves were then inoculated with TuMV tagged with GFP and were cultivated for 5 days. Exposure to both metal- and carbon-based NMs significantly increased the shoot biomass by approximately 50%. TEM images demonstrated that exposure to NMs did not alter cellular integrity; both NP Fe2O3 and TiO2 preferentially accumulated in chloroplasts. Fluorescence images of TuMV abundance on the leaf surfaces suggest that NMs significantly inhibited viral proliferation as measured by the fluorescence intensity on the newly emerged leaves. Approximately 15-60% decreases in the relative amount of TuMV coat proteins could further explain the mechanisms by which NMs suppressed viral infection. Increases in phytohormone levels of 40% also suggest that NMs play an important role in stimulating plant growth and activating defense mechanisms. These findings contribute to our understanding of the sustainable use of ENMs in agriculture.