Identification of Low-Nitrogen-Related miRNAs and Their Target Genes in Sugarcane and the Role of miR156 in Nitrogen Assimilation

Abstract

Chemical nitrogen (N) fertilizer is widely used in sugarcane production, especially in China and India. Understanding the molecular mechanisms and mining miRNAs and their target genes associated with nitrogen use efficiency (NUE) in sugarcane can aid in developing the N-efficient varieties, and thus is beneficial to reduce N fertilizer application. In this study, the root miRNA database of N-efficient sugarcane variety ROC22 under low N stress (0.3 mM NH4NO3) for 3 h was constructed, along with their transcriptome-rearranged data. KEGG analysis indicated that those candidate target genes, corresponding to differentially expressed miRNAs, were mainly enriched in N metabolism, amino acid metabolism, carbohydrate metabolism, photosynthesis, and hormone signal transduction pathways. It was found that under low N stress for 0–24 h, there was a negative correlation between miR168 and SPX, along with miR396 and acnA. Furthermore, the expression of miR156 in the roots of ROC22 was significantly up-regulated under low N treatment. Compared with the wild-type, the Arabidopsis plants overexpressing sugarcane miR156 exhibited significantly improved length and surface area of roots, while the expression of one NO3- transporter gene NRT1.1, three N assimilation key genes (NR1, NIR1, and GS), and the activity of two N assimilation key enzymes (NR and GS) were up-regulated under low N treatment. It can be reasonably deduced that sugarcane miR156 can enhance the nitrogen assimilation ability of the overexpressed Arabidopsis plants under low N application, and thus has a potential ability for improving sugarcane NUE. The present study should be helpful for understanding the molecular regulatory network in the N-efficient sugarcane genotype responding to low N stress and could provide the candidate miRNAs with a potential function in improving sugarcane NUE.

Update on functional analysis of long non-coding RNAs in common crops

“…A long intergenic noncoding RNA (lincRNA) with significant complementarity to miR408 was predicted to act as miRNA bait, with inhibitory effects on the regulation of canonical miR408 targets (Thiebaut et al, 2017). Other studies showed that miRNAs influence sugarcane growth and development, stress resistance, and other processes Gao et al, 2022). The research conducted to date on sugarcane lncRNAs has primarily relied on predictions, which will need to be experimentally verified.…”

Light-Dependent Regulatory Interactions between the Redox System and miRNAs and Their Biochemical and Physiological Effects in Plants

“…The expression of the H 2 O 2 -responsive miR156 [100] was affected by low light intensity, red, far-red, and blue light [142,148,149]. Overexpressing of sugarcane miR156 in Arabidopsis up-regulated key genes of nitrate reduction and amino acid synthesis (GLUTAMINE SYN-THASE) [157], for which processes the modulating effect of light intensity, blue, red, and far-red spectral components was shown in wheat [67]. Certain amino acids, in turn, affect the redox homeostasis through their involvement in the formation of GSH (Cys, Glu, Gly) or the consumption/production of reducing power during their metabolism (for instance Pro-NADPH); therefore, feedback control may function for the light-dependent modulation of nitrogen metabolism by miR156 and the redox system.…”