FIGURE 5.

Apoplast with viral particles is infectious by rub inoculation, but not by infiltration. (a) Infected foci and green fluorescent spots were observed on the rub‐inoculated side of the leaf at 4 days postinoculation, but not on the infiltrated side of the leaf. Western blot with anti‐coat protein (CP) antibody confirmed infection by potato virus X (PVX) on the rub‐inoculated side of the leaf. (b) Apoplasts from mock‐inoculated (left) or PVX‐infected (right) leaves were centrifuged at 40,000 × g to extract exosomes and observed by transmission electron microscopy. Exosomes (red arrowhead) were detected in both samples and viral particles (white arrows) in the infected sample but independently of the exosomes. Scale bar = 100 nm