The DNA G-Quadruplex-Stabilizing Ligand TMPyP4 Inhibits Maize Radicle Growth by Modulating Reactive Oxygen Species Homeostasis.

G-quadruplex (DG4) is folded in guanine-rich DNA sequences and regulates DNA replication and transcription. Although bioinformatics analyses have predicted the presence of DG4 in maize, its biological functions remain largely unexplored. In this study, we treated maize seedlings with 0, 100, 200, and 300 μM TMPyP4, a DG4-stabilizing ligand, and observed that TMPyP4 inhibits radicle growth by increasing reactive oxygen species (ROS) levels and inducing DNA fragmentation in radicle cells. Transcriptomic RNA-seq revealed that TMPyP4 modulated the expression of 1614 genes in maize radicle cells, which were predominantly associated with redox reactions, membrane components, and secondary metabolic pathways. BG4-ChIP-seq analysis demonstrated that DG4 structures are evenly distributed across the ten chromosomes of the maize genome, occupying 22,449 loci and showing significant enrichment for specific DG4-binding motifs. Integrative analysis of RNA-seq data and BG4-ChIP-seq identified 944 differentially expressed genes, which were significantly enriched in pathways related to redox reactions and secondary metabolism. Collectively, these findings suggest that DG4-stabilizing ligands regulate maize radicle growth by modulating ROS homeostasis, providing critical insights into the functional roles of DG4s in maize.