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

Abstract

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. Overexpression of a miR393-resistant form of TIR1 (mTIR1) enhanced auxin sensitivity and led to pleiotropic effects on plant development including inhibition of primary root growth, overproduction of lateral roots, altered leave phenotype and delayed flowering. Furthermore, miR393 level was increased in 35S:mTIR1 plant, suggesting that TIR1 promoted the expression of miR393 by a feedback loop. The interaction between miR393 and its target indicates a fine adjustment to the roles of the miR393-TIR1 module, which is required for auxin responses in plant development.

Functional plasticity of miR165/166 in plant development revealed by small tandem target mimic

“…Furthermore, a number of HD-Zip genes and miRNAs in plants have been implicated in auxin signaling and transport, and drought responses [27][28][29]. To investigate if miR165/166 and HD-ZIP III could respond to abiotic stresses, we firstly analyzed the cis-elements in the promoter regions of miR165/166 and HD-ZIP III genes.…”

“…On the other hand, a subset of HD-Zip family I and II genes are reported to be involved in ABA-mediated adaptation to drought stress [27][28][29]. Many stress-responsive cis-elements were found in the promoter regions of miR165/166 and HD-ZIP III genes, implicating that the miR165/166 and HD-ZIP III genes may directly contribute to the increased salt tolerance of STTM165/166-31 overexpressed seedlings.…”

A plant microRNA regulates the adaptation of roots to drought stress

“…Since the F-box auxin receptors TIR1, AFB1, AFB2 and AFB3 are involved in root system morphology [15,23], we checked the transcript levels of these receptor genes in fry1. However, no significant differences were detected in the full-length mRNA levels of TIR1, AFB1, AFB2, and AFB3 between the wild type and fry1 ( Fig.…”

A Conifer ABI3-Interacting Protein Plays Important Roles during Key Transitions of the Plant Life Cycle

“…before seedlings were 2 weeks old). In Arabidopsis and other species, auxin plays a vital role in lateral root development (Casimiro et al, 2001;Marchant et al, 2002;Dubrovsky et al, 2008;Fukaki and Tasaka, 2009;Chen et al, 2011;Moriwaki et al, 2011;Zhu et al, 2012). It is important to note that CnAIP2 expression was strongly promoted by auxin.…”