Fig. 1

AGO1 mediates all-round functions with endogenous and exogenous sRNAs. (1) Plant miR168 and AGO1 forming an autoregulatory loop in which AGO1 stabilizes miR168, whereas miR168 suppresses AGO1 expression. (2–3) AGO1-sRNA suppresses plant mRNAs that may play crucial roles in plant growth and development (2) and be involved in plant PTI and ETI against pathogens (3), such immunities have trade-offs with growth and development. (4) Pathogenic fungi and oomycetes may generate sRNAs that can be loaded into plant AGO1 to hijack the host RNAi pathway to facilitate their infection. (5) Viral infections may induce the expression of miR168 to suppress AGO1 expression, thereby facilitating infection. (6) Rice AGO18 competes with AGO1 for binding miR168 to alleviate its repression on AGO1 and mounts antiviral immunity. (7–8) AGO1 may bind to vsiRNAs to mediate defense against viruses (7) or to silence plant endogenous genes for facilitating infection (8). (9–12) Virus-encoded suppressors of RNAi (VSRs) may promote viral infection via sequestering the host’s sRNAs (9), or bind to AGO1 and mediate AGO1 degradation (10), or inhibit AGO1 cleavage activity (11), or block RISC activity (12). (13) JA and IAA can promote AGO1 binding to chromatin to enhance the expression of stimuli-responsive genes. (14–15) ABA induces the expression of AGO1 and the abundance of mature miR168 (14), whereas SA inhibits the expression of AGO1 (15). (16) BRs inhibit the distribution of AGO1 at the ER, thereby inhibiting miRNA-mediated transcriptional repression