Figure 2.

Hosts and pathogens are engaged in an arms race mediated by sRNAs. In plant–pathogen interactions, plants recognize PAMPs (pathogen-associated molecular pattern) with PRRs (pattern recognition receptor) to trigger innate immunity against most pathogen infections. Pathogens, in turn, secrete effectors including effector proteins and some sRNAs to facilitate infection. Some plant NB-LRR proteins are activated by effector proteins, triggering the second layer of immunity response, the so-called ETI. Additionally, hosts simultaneously export siRNAs and miRNAs to induce cross-kingdom gene silencing in the pathogen. Some plant miRNAs targeting disease resistance genes can be decoyed by certain specific lncRNAs, which attenuates the repression of miRNAs on their targets. EV: extracellular vesicles; TTSS: type Ⅲ secretion system. (Question symbols indicate predicted characteristics that need further mining).