Involved in miRNAs and siRNAs biogenesis and thus promotes gene silencing (PubMed:23071326). Modulates auxin (IAA) transport-related developmental programs by regulating protein phosphatase 2A (PP2As)-driven auxin efflux carrier PIN proteins recycling and polarity (PubMed:26888284). Required during development (PubMed:23071326, PubMed:26888284). Necessary for abiotic stress (e.g. chilling and salt) tolerance (PubMed:23071326). Interacts with ubiquitin thioesterases UBP12 and UBP13, and with protein phosphatase 2A subunits PP2AB1, PP2AB2, PP2A3, PP2A4, PP2AA1 and PP2AA2. Colocalizes with miRNA biogenesis components in distinct subnuclear bodies (PubMed:23071326). Localized in the nuclei, excluding the nucleolus, in all cells of the root apical meristem. In young cortical cells of the root, localized in the nucleus and cytosol (PubMed:26888284). Expressed in the shoot apical meristem (SAM), embryos, seedlings, root tips, and root and leaf primordia. Localized in the shoot apical meristem (SAM) dome, the emerging leaf and root primordia, the provascular strands of developing seedlings, and the epidermis and cortex of the meristematic and elongation zones of the primary root tip, and in the protoderm of heart- and torpedo- stage embryos. Developmental defects due to abnormal miRNAs and siRNAs biogenesis including serrated, sickle-like leaf margin, reduced height, delayed flowering, and abnormal inflorescence phyllotaxy. Hypersensitivity to chilling and salt stresses (PubMed:23071326). Several symptoms associated with alteration in auxin (IAA) signaling such as increased IAA levels in shoot apices and reduced IAA accumulation in root meristems, reduced apical dominance and abnormal root gravitropism, growth and emergence. Altered PIN polarity and endocytosis in specific cells (PubMed:26888284).