Involved in the RNA silencing pathway. May bind to short RNAs such as microRNAs (miRNAs) or short interfering RNAs (siRNAs), and represses the translation of mRNAs which are complementary to them (By similarity). Regulates shoot apical meristem (SAM) initiation and maintenance and leaf polarization through the trans-acting siRNAS (ta-siRNAs) pathway which probably modulates the expression of the ARF2, ARF3, ARF4, ARF14 and ARF15 genes. Expressed in the reproductive shoot apex. Lack of the shoot apical meristem (SAM) in the embryo, but formation of radicle and scutellum. In weak alleles, formation of an incomplete SAM and abnormal leaves production. Belongs to the argonaute family. Ago subfamily.