microRNAs in Plant Embryogenesis

Abstract

Plants show a remarkable developmental plasticity to adapt their growth to changing environmental conditions. Recently small non-coding RNAs and microRNAs have been identified by their role in the regulation of gene expression and functions in development and in response to the environment. Plant microRNAs have been grouped into ancient and recently formed miRNAs. The ancient types are highly conserved in the plant kingdom. The oldest miRNAs tend to be highly expressed in plant cells and usually perform more fundamental tasks, whereas young miRNAs are often less abundant and are induced by specific conditions.Plant miRNAs target only a small number of mRNAs; however, by largely targeting transcription factor genes, they act in key biological processes, performing metabolic functions, responding to abiotic and biotic stresses, and guiding developmental trajectories. Moreover, miRNAs are regulators of plant-microbe interactions, and several miRNAs move through the phloem from leaves to roots as effectors of plant response to environment factors. The ability to regulate plant microRNA functions opens new perspectives in the field of crop improvement. © 2013 Woodhead Publishing Limited. All rights reserved.