Carbon-based nanomaterials suppress tobacco mosaic virus (TMV) infection and induce resistance in Nicotiana benthamiana

Although nanomaterials (NMs) may inhibit viral pathogens, the mechanisms governing plant-virus-nanomaterial interactions remain unknown. Nicotiana benthamiana plants were treated with nanoscale titanium dioxide (TiO2) and silver (Ag), C-60 fullerenes, and carbon nanotubes (CNTs) at 100, 200 and 500 mg L-1 for a 21-day foliar exposure before inoculation with GFP-tagged tobacco mosaic virus (TMV). Plants treated with CNTs and C-60 (200 mg L-1) exhibited normal phenotype and viral symptomology was not evident at 5 days post-infection. TiO2 and Ag failed to suppress viral infection. RT-qPCR analysis revealed that viral coat protein transcript abundance and GFP mRNA expression were reduced 74-81% upon CNTs and C-60 treatment. TEM revealed that the chloroplast ultrastructure in carbon NM-treated plants was unaffected by TMV infection. Fluorescence measurement of CNTs and C-60 (200 mg L-1) treated plants indicated photosynthesis equivalent to healthy controls. CNTs and C-60 induced upregulation of the defense-related phytohormones abscisic acid and salicylic acid by 33-52%; the transcription of genes responsible for phytohormone biosynthesis was elevated by 94-104% in treated plants. Our findings demonstrate the protective role of carbon-based NMs, with suppression of TMV symptoms via hindered physical movement and viral replication. Given the lack of viral phytopathogen treatment options, this work represents a novel area of nano-enabled agriculture.

Automated summary

The study demonstrates the protective role of carbon-based nanomaterials in inhibiting viral symptoms by hindering physical movement and viral replication. Plants treated with carbon nanomaterials showed normal phenotype and reduced viral infection symptoms, with photosynthesis comparable to healthy controls. Upregulation of defense-related phytohormones and transcription of genes responsible for phytohormone biosynthesis were also observed in treated plants.