miRNAs in the crosstalk between phytohormone signalling pathways.

Phytohormones are signal molecules produced within the plant that control its growth and development through the regulation of gene expression. Interaction between different phytohormone pathways is essential in coordinating tissue outgrowth in response to environmental changes, such as the adaptation of root development to water deficit or the initiation of seed germination during imbibition. Recently, microRNAs (miRNAs) have emerged as key regulators of phytohormone response pathways in planta by affecting their metabolism, distribution, and perception. Here we review current knowledge on the miRNA-mediated regulations involved in phytohormone crosstalk. We focus on the miRNAs exhibiting regulatory links with more than one phytohormone pathway and discuss their possible implication in coordinating multiple phytohormone responses during specific developmental processes.