Total protein extracts from plant samples were prepared and resolved by SDS-PAGE, as described (Pasin et al. 2020 (link)). Immuno-detection was conducted using a rabbit anti-TVMV coat protein serum (Domier et al. 1989 (link)) as the primary antibody, and a peroxidase goat anti-rabbit IgG (Jackson ImmunoResearch Laboratories) as the conjugate. Virion micrographs were obtained by immunosorbent electron microscopy as described (Valli et al. 2014 (link)). Briefly, plant extracts were prepared in 5 mM Tris-HCl (pH 7.5), 150 mM NaCl, 2.5 mM DTT, and incubated with collodion-coated carbon-stabilized copper grids precoated with the anti-TVMV CP serum. Grids were negative-stained with 2% uranyl acetate and observed in a transmission electron microscope (JEM 1011, Jeol); images were taken with the ES1000W Erlangshen CCD camera (Gatan). ImageJ (Schneider et al. 2012 (link)) was used for image processing.