miRNA Profiling Reveals the Role of Gibberellin Signaling Pathway in Low-Nitrogen Stress Adaptation of Xinjiang...

Understanding the molecular mechanisms of low-nitrogen (LN) tolerance in common wheat (Triticum aestivum L.) is crucial for developing cultivars with improved nitrogen-use efficiency (NUE). In this study, a LN-tolerant cultivar ('Xin Chun 29', XC29) and a LN-sensitive cultivar ('Xin Chun 11', XC11) were used to investigate miRNA-mediated post-transcriptional regulation under LN stress. A total of 822 miRNAs were identified across root and grain tissues, including 104 known miRNAs and several tissue-specific candidates. In roots, tae-miR395a and tae-miR444a were significantly upregulated in XC29 under LN stress, putatively targeting an F-box ubiquitin ligase gene and glutathione reductase gene, respectively. In grains, the tae-miR156/SBP module was upregulated in XC29, whereas tae-miR1118 and tae-miR9778 were downregulated in XC11, potentially suppressing a receptor kinase gene and calmodulin gene. KEGG analysis revealed that target genes of differentially expressed miRNAs were significantly enriched in plant hormone signal transduction, ubiquitin-mediated proteolysis, and nitrogen metabolism. Notably, within the hormone signaling category, the gibberellin (GA) branch was highlighted by the co-targeting of DELLA genes by tae-miR1130b-3p and tae-miR1120c-3p. To elucidate this regulatory hub, a putative miRNA-target network centered on DELLA proteins was constructed, further underscoring the centrality of gibberellin signaling in the LN adaptation process. These findings suggest potential key miRNA-target modules contributing to LN adaptive responses and may provide useful genetic resources for molecular design breeding of nitrogen-efficient wheat.