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.

Cotton Verticillium wilt (VW), caused by the soil-borne fungus Verticillium dahliae (V. dahliae), is a devastating disease that poses a serious threat to sustainable cotton production worldwide. Protein methylation plays a critical role in fungal adaptation to the host environment and manipulation of plant immunity. Protein arginine methyltransferases (PRMTs) are key enzymes catalyzing arginine methylation, yet their functions in V. dahliae pathogenicity remain largely unexplored. In this study, we identified VdPRMT4 in V. dahliae through homology-based screening. qRT-PCR analysis revealed that VdPRMT4 transcript levels were significantly increased during the early stages of V. dahliae infection in cotton. HIGS assays showed that silencing VdPRMT4 markedly alleviated cotton VW symptoms and reduced fungal biomass in cotton plants. Gene knockout and complementation experiments demonstrated that deletion of VdPRMT4 did not affect hyphal growth but significantly impaired sporulation capacity and severely attenuated pathogenicity on cotton. Transcriptomic analysis further indicated that loss of VdPRMT4 profoundly affected the metabolic pathways of V. dahliae, including protein processing in the endoplasmic reticulum, purine metabolism, and glycerolipid metabolism. Collectively, this study provides the first evidence that VdPRMT4 plays a critical role in stress adaptation and pathogenicity of V. dahliae, offering new insights into fungal pathogenesis and identifying potential targets for VW control.