Micro RNA mediated regulation of nutrient response in plants: the case of nitrogen

Micro RNAs (miRNAs) regulate their target genes, that are crucial for plant adaptation to perturbations in environmental variables and nutrient availability by the changes in their own abundance. The greatest limiting factors for the growth of plants are the changing environment and a scarcity of inputs. Nitrogen (N) is an essential nutrient for plant growth as it is a constituent of proteins and photosynthetic pigments, two of plants’ most important components. Consequently, the identification of N stress-responsive miRNAs represents a significant research milestone. Several miRNAs related to nutrient stress and accompanying signalling pathways have been discovered in the past decade. This review focuses on the miRNAs associated with nutrient deficiency, their potential targets, and how their expression varies in response to different nutrient stresses, with a focus on N stress. Increased levels of miR169a, for example, induce down-regulation of NFYA family members, repressing NPF6.3 and NRT2.1 expression and decreasing nitrate ion accumulation. Another miRNA, miR167, regulates auxin Response Factors ARF6 and ARF8. The miR167 and its target ARF8 are engaged in lateral root development in response to nitrate. Root growth is likewise linked to miR164 and its target NAC1. The expression of miR164 is upregulated under low-nitrate conditions. N deprivation also increases the expression of miR826 and miR5090, which inhibits the AOP2 gene, which is implicated in glucosinolate biosynthesis. Plants overexpressing miR826 and miR5090 have lower glucosinolate levels, higher biomass accumulation, more lateral roots, higher chlorophyll content, reduced anthocyanin content, and higher NRT2.1 expression, all of which result in better N stress tolerance. This review could provide a thorough understanding of such miRNAs and their functions. Finally, the generation of transgenic plants, mutants, or artificial miRNAs (amiRNAs) can serve as the way forward for generating stress-tolerant and nutrient-efficient plants.