DOUBLE-STRANDED RNA BINDING (DRB) proteins DRB1, DRB2, and DRB4 are essential for microRNA (miRNA) production in 
Arabidopsis thaliana (
Arabidopsis) with miR160, and its target genes, 
AUXIN RESPONSE FACTOR10 (
ARF10), 
ARF16, and 
ARF17, forming an auxin responsive miRNA
            
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            DOUBLE-STRANDED RNA BINDING (DRB) proteins DRB1, DRB2, and DRB4 are essential for microRNA (miRNA) production in 
Arabidopsis thaliana (
Arabidopsis) with miR160, and its target genes, 
AUXIN RESPONSE FACTOR10 (
ARF10), 
ARF16, and 
ARF17, forming an auxin responsive miRNA expression module crucial for root development. 
Methods: Wild-type 
Arabidopsis plants (Columbia-0 (Col-0)) and the 
drb1, 
drb2, and 
drb12 mutants were treated with the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D), and the miR160-mediated response of these four 
Arabidopsis lines was phenotypically and molecularly characterized. 
Results: In 2,4-D-treated Col-0, 
drb1 and 
drb2 plants, altered miR160 abundance and 
ARF10, 
ARF16, and 
ARF17 gene expression were associated with altered root system development. However, miR160-directed molecular responses to treatment with 2,4-D was largely defective in the 
drb12 double mutant. In addition, via profiling of molecular components of the miR160 expression module in the roots of the 
drb4, 
drb14, and 
drb24 mutants, we uncovered a previously unknown role for DRB4 in regulating miR160 production. 
Conclusions: The miR160 expression module forms a central component of the molecular and phenotypic response of 
Arabidopsis plants to exogenous auxin treatment. Furthermore, DRB1, DRB2, and DRB4 are all required in 
Arabidopsis roots to control miR160 production, and subsequently, to appropriately regulate 
ARF10, 
ARF16, and 
ARF17 target gene expression.
            
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