ARGONAUTE 1: a node coordinating plant disease resistance with growth and development

Argonaute (AGO) proteins are highly conserved and widely distributed across various organisms. They mainly associate with small RNAs (sRNAs) and act as integral players of the RNA-induced silencing complex in the RNA interference (RNAi) pathway, regulating gene expression at transcriptional and post-transcriptional levels, thereby mounting diverse fine-tuning functions in a variety of biological processes. Since the discovery and functional characterization of the first AGO in Arabidopsis, our understanding of the functions of AGO proteins has grown rapidly throughout the plant kingdom. AGO1 attracts investigators’ attention because it forms an autoregulatory loop with miR168 and associates with other endogenous sRNAs and cross-kingdom exogenous sRNAs to relay all-round functions. AGO1 associates with endogenous sRNAs that form a complicated regulatory network via targeting a large body of downstream genes involved in growth, development, and stress-induced responses. Host AGO1 may also be exploited by cross-kingdom exogenous sRNAs generated by parasitic organisms to facilitate their colonization via suppressing host defense genes. Moreover, many pathogenic microbes directly target host AGO1 to facilitate their infection via suppression of the host RNAi pathway. Thus, we focus on plant AGO1 and provide an overview of our current understanding of the roles of AGO1 in the coordination of plant disease resistance with growth and development. We also discuss the perspectives in the dissection of the AGO1-mediated signal transduction pathway.