The Role of Rice microRNAs in Abiotic Stress Responses

microRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression at the posttranscriptional level by mRNA cleavage or translation inhibition. They play diverse roles in plant growth and development as well as abiotic stress responses. In response to abiotic stresses such as drought, salt, cold, heat, and nutrient limitations, the expression levels of some miRNAs change, resulting in a modulation of the expression patterns of miRNA target genes that are associated with stress adaptations. In rice, stress-responsive miRNAs have been identified and characterized, and conserved regulation of conserved miRNAs as well as new regulation by conserved miRNAs and rice-specific miRNAs is evident. The regulatory mechanisms controlling target gene expression by stressresponsive miRNAs include both the coherent and incoherent regulatory networks that are dynamic and complex. A better understanding of the regulation of miRNAs and targets during stress responses can contribute to rice breeding for improving yield, quality and tolerance to abiotic stresses. Here, we review current advances in the area of rice miRNAs and target RNAs associated with abiotic stresses and discuss how they relate to miRNA-mediated stresstolerance.