Plant ARGONAUTEs: Features, Functions, and Unknowns.

ARGONAUTEs (AGOs) are the effector proteins in eukaryotic small RNA (sRNA)-based gene silencing pathways controlling gene expression and transposon activity. In plants, AGOs regulate key biological processes such as development, response to stress, genome structure and integrity, and pathogen defense. Canonical functions of plant AGO-sRNA complexes include the endonucleolytic cleavage or translational inhibition of target RNAs and the methylation of target DNAs. Here, I provide a brief update on the major features, molecular functions, and biological roles of plant AGOs. A special focus is given to the more recent discoveries related to emerging molecular or biological functions of plant AGOs, as well as to the major unknowns in the plant AGO field.