ARF5/MONOPTEROS directly regulates miR390 expression in the Arabidopsis thaliana primary root meristem

Abstract

The root meristem is organized around a quiescent center (QC) surrounded by stem cells that generate all cell types of the root. In the transit‐amplifying compartment, progeny of stem cells further divides prior to differentiation. Auxin controls the size of this transit‐amplifying compartment via auxin response factors (ARFs) that interact with auxin response elements (AuxREs) in the promoter of their targets. The microRNA miR390 regulates abundance of ARF2, ARF3, and ARF4 by triggering the production of trans‐acting (ta)‐siRNA from the TAS3 precursor. This miR390/TAS3/ARF regulatory module confers sensitivity and robustness to auxin responses in diverse developmental contexts and organisms. Here, we show that miR390 is expressed in the transit‐amplifying compartment of the root meristem where it modulates response to exogenous auxin. We show that a single AuxRE located in miR390 promoter is necessary for miR390 expression in this compartment and identify that ARF5/MONOPTEROS (MP) binds miR390 promoter via the AuxRE. We show that interfering with ARF5 / MP ‐dependent auxin signaling attenuates miR390 expression in the transit‐amplifying compartment of the root meristem. Our results show that ARF5/MP regulates directly the expression of miR390 in the root meristem. We propose that ARF5, miR390, and the ta‐siRNAs‐regulated ARFs modulate the response of the transit‐amplifying region of the meristem to exogenous auxin.

Epigenetic Regulation of Auxin-Induced Somatic Embryogenesis in Plants

“…The complex miRNA-mediated regulatory network of SE induction considers feedback loops between the miRNA and the targets. Accordingly, miR390-targeted ARF5/MONOPTEROS (MP) was recently found to bind auxin-responsive elements (AuxRE) in the promoter of the MIR390a gene to control the MIR390 expression in the root meristem [109]. Although both ARF5/MP and miR390 have been suggested to control SE induction in Arabidopsis, their regulatory interactions in this process require experimental validation [55,93].…”

The PLETHORA/PIN-FORMED/AUXIN network mediates terminal prehaustorium formation in the parasitic plant Striga hermonthica

“…Low levels of auxin have been shown to stimulate root growth and delay root differentiation (Dastidar et al, 2019). Hence, we investigated whether the application of auxin at low concentrations prevents Striga meristem differentiation and delays haustorium formation.…”

The molecular regulation of cell pluripotency in plants

“…The Arabidopsis miR160 inhibits pluripotent callus formation via the cleavage of ARF10 mRNAs, which plays a role in the distal root stem cell differentiation by defining spatial expression patterns of the root stem cell regulators, such as WOX5 and PLTs, as well as a cytokinin signaling gene ARR15 (Ding and Friml 2010;Liu et al 2016). In addition, the ARF5/ MONOPTEROS (MP), which encodes a transcription factor activated by the auxin signaling pathway and directly regulates miR390 expression in the Arabidopsis primary root meristem (Dastidar et al 2019), also plays a role in conferring shoot-regeneration competence to the calluses generated from leaf, petiole, or root explants on CIM (Ckurshumova et al 2014).…”