Regulation of auxin response by miR393-targeted transport inhibitor response protein 1 is involved in normal development in Arabidopsis.

miR393, which is encoded by MIR393a and MIR393b in Arabidopsis, post-transcriptionally regulates mRNAs for the F-box auxin receptors TIR1 (Transport Inhibitor Response Protein 1), AFB1 (Auxin Signaling F-box Protein 1), AFB2 and AFB3. However, biological functions of the miR393-TIR1/AFBs module in auxin response and plant development is not fully understood. In the study herein, we demonstrate that miR393 accumulated in response to exogenous IAA treatment, and its induction was due to enhanced MIR393b transcription but not MIR393a.