The Double-Stranded RNA Binding Proteins DRB1 and DRB2 Are Required for miR160-Mediated Responses to Exogenous Auxin.

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