A Phytophthora Effector Suppresses Trans-Kingdom RNAi to Promote Disease Susceptibility (Cell Host & Microbe)

The role of plant RNAi in defense against eukaryotic pathogens is unclear. Hou et al. report that Arabidopsis produces a reservoir of secondary siRNAs that confer resistance against the notorious pathogen Phytophthora, likely through trans-kingdom gene silencing. However, a Phytophthora effector defeats this defense by specifically inhibiting secondary siRNA biogenesis.