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. 2022 Feb 18;13:824240. doi: 10.3389/fpls.2022.824240

Figure 2.

Figure 2

Model for the role of miRNAs in shoot apex. miR394 synthesized at the protoderm represses LCR in subtending cells, which leads to the activation of the WUSCHEL (WUS) transcription factor to maintain stem cell identity and CLAVATA3 (CLV3) peptide expression. ARGONAUTE10 (AGO10) specifically sequesters miR165/166 and antagonizes its activity in the meristematic cells, thus regulating SAM and AM development. ARGONAUTE1 (AGO1) is expressed ubiquitously in the apex, recruit miR165/166 to form RNA-induced silencing complex (RISC). The adaxial and abaxial domains of leaves are established during leaf primordia emergence. HD-ZIP III transcription factors are restricted to the adaxial side by the action of miR165/166. In turn, AUXIN RESPONSE FACTOR 2/3/4 are restricted to the abaxial side by the action of TAS3 ta-siRNA. Two NAC-domain transcription factors are post-transcriptionally regulated by miR164 in embryonic meristem initiation, boundary size control, and cotyledon establishment. miR319 and miR396 target several TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) and Growth-Regulating Factor (GRF) genes, respectively, and act coordinately to control leaf cell proliferation and differentiation. miR156 and miR171 synergistically regulate trichome initiation by targeting SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) and LOST MERISTEMS (LOM), respectively. Arrows indicate positive regulation, whereas the dotted lines with perpendicular end bars represents a hypothesized negative regulation.