Suzuki et al. (2019) found that infection of DCL2- and -4-silenced tomato plants with PSTVd leads to systemic necrosis associated with induction of miR398s and a decrease in the expression of their target gene CCS1. Consistently, in this study, systemic necrosis in AGO2-knockdown tomato plants infected with PVX was also associated with the induction of miR398s and a decrease in CCS1 transcript level. Here, AGO2 is linked to infection.