TOP1alpha-Mediated Stabilization of CYP82C4 G-Quadruplex DNA Represses Lateral Root Primordium Initiation in Arabidopsis (PRJCA040774)
Lateral roots (LRs) are indispensable part of the plant root system and influence nutrient uptake and environmental adaptability. Chromatin remodeling plays a key regulatory role in LRs development by modulating gene expression. However, how chromatin regulates this process remains largely unknown. Here, we found that the TOPOISOMERASE1 ALPHA (TOP1a), as essential chromatin remodeling factor, significantly inhibited lateral root primordium (LRP) density in Arabidopsis thaliana. Transcriptomic and CUT&Tag analyses indicated that CYP82C4 was most up-regulated in the loss-of-function mutant line top1a. Further biophysical study demonstrated that a 19-nt G-rich DNA (T19) was fold into an antiparallel G-quadruplex (G4) structure in the template strand of CYP82C4. In Arabidopsis root, the T19 was significantly enriched in top1a. CD melting and SPR assays confirmed that TOP1a stabilized T19 DNA G-quadruplex with high affinity in vitro. G4-mutant lines and G4 destabilizing ligand treatment both showed that CYP82C4 expression increased when G4 structure failed to form properly, which promoted LRP initiation. These results demonstrated that AtTOP1a inhibited LRP initiation by suppressing CYP82C4 expression through stabilizing the T19 DNA G-quadruplex. Together, our findings uncover a novel mechanism by which AtTOP1a drives chromatin remodeling to regulate lateral root initiation through its action on G-quadruplex structures.