MicroRNA-mediated signaling and regulation of nutrient transport and utilization.

MicroRNAs (miRNAs), a group of small-RNA regulators, control diverse developmental processes and stress responses. Recent studies of nutrient-responsive miRNAs have offered novel insights into how plants regulate gene expression to coordinate endogenous demand and external availability of nutrients. Here, we review the mechanisms mediated by miRNAs to facilitate nutrient transport and utilization and show that miRNAs: first, control nutrient uptake and translocation by targeting nutrient transporters or their regulators; second, adjust nutrient metabolism by redistributing nutrients for biosynthesis of more essential compounds; and third, modulate root development and microbial symbiosis to exploit soil nutrients. We also highlight the long-distance movement of miRNAs in maintaining whole-plant nutrient homeostasis and propose several directions for future research.