Trans-kingdom RNAi in plant–pathogen interactions: mechanisms and biocontrol strategies

The exchange of secondary metabolites or proteins between plants and phytopathogens has long been a central topic in plant–pathogen interaction. In recent decades, small RNAs (sRNAs) have emerged as key effectors during plant–pathogen interaction. RNA interference (RNAi) induced by foreign sRNA across species boundaries, known as trans-kingdom RNAi, plays crucial roles in regulating both plant defense and pathogen virulence. Beyond its biological significance, trans-kingdom RNAi is gaining attention as a promising strategy for sustainable crop disease management through RNAi-based biocontrol. In this review, we summarize recent advances in understanding the mechanisms of trans-kingdom RNAi and three major RNAi-based technologies for pathogen control, along with their practical applications. We also discuss the definition and functional mechanism of suppressor of trans-kingdom RNAi (STR) proteins. A deeper understanding of these mechanisms holds great potential for developing innovative approaches to crop protection.