miRNAomic Approach to Plant Nitrogen Starvation

Abstract

Nitrogen (N) is one of the indispensable nutrients required by plants for their growth, development, and survival. Being a limited nutrient, it is mostly supplied exogenously to the plants, to maintain quality and productivity. The increased use of N fertilizers is associated with high-cost inputs and negative environmental consequences, which necessitates the development of nitrogen-use-efficient plants for sustainable agriculture. Understanding the regulatory mechanisms underlying N metabolism in plants under low N is one of the prerequisites for the development of nitrogen-use-efficient plants. One of the important and recently discovered groups of regulatory molecules acting at the posttranscriptional and translational levels are microRNAs (miRNAs). miRNAs are known to play critical roles in the regulation of gene expression in plants under different stress conditions including N stress. Several classes of miRNAs associated with N metabolism have been identified so far. These nitrogen-responsive miRNAs may provide a platform for a better understanding of the regulation of N metabolism and pave a way for the development of genotypes for better N utilization. The current review presents a brief outline of miRNAs and their regulatory role in N metabolism.

MicroRNA Mediated Plant Responses to Nutrient Stress

“…miRNA functions have been investigated in response to nitrate and N deficiency in the past few years. In response to N, miR167 and miR393 restrict root growth [ 24 ]. Moreover, several other N starvation responsive miRNAs have been discovered in plants using in situ hybridization, small RNA (sRNAs) sequencing at high efficiency, real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and hybridization microarray analyses ( Table 1 ).…”

“…Nitrate regulation of lateral root emergence was completely lost in genetically modified plants expressing miR167 and ARF8 blank mutants. Consequently, the miR167 or ARF8 module controls adventitious root plants’ responses to N, and even more so, N metabolic enzymes that are produced by downstream of nitrification and absorption [ 24 ]. Furthermore, it was discovered that miR167 is extra sensitive to N deficiency in maize [ 28 ] and in Arabidopsis [ 29 ] indicating that miR167 has vital roles in monocots and dicots’ adaptation to N-limited conditions.…”