The dynamic regulation of microRNAs circuits in plant adaptation to abiotic stresses: A survey on molecular, physiological and methodological aspects

Being sessile organisms, plants continuously face a complex array of environmental stresses and have naturally evolved multifaceted but well-coordinated adaptive responses to cope with them. Recent studies in various plant species and varieties have established microRNAs (miRNAs) as key elements in the post-transcriptional regulation of response to abiotic stresses. However, despite their critical role has been widely recognized, the joint action of miRNAs with the main pathways of response is still far from being completely clarified. Moreover, little is still known on the control of the biogenesis and maturation of stress responsive miRNAs. Here we give an overview on the involvement of microRNAs in plant response to nitrogen and phospho- rous deprivation and on their less characterized role in the plant response to hypoxia and cold. Nitrogen and phosphorous are the most limiting nutrients for agricultural production and the plant responsive- ness to their deficiency is significantly regulated at the transcriptional and post-transcriptional level. We reported the different miRNAs families involved, which sometimes are also common to different species and other nutrient or abiotic stresses. Indeed we reported that some miRNAs families involved in N and P deprivation are also acting in hypoxia and cold stresses. The results of the few existing studies on the miRNAs involvement on low oxygen and cold conditions are also described. Furthermore, we reviewed recent progress on methods for microRNAs localization/quantification and de novo identification, by exploring the main tools available and used