WUSCHEL-dependent chromatin regulation in maize inflorescence development at single-cell resolution

BACKGROUND: WUSCHEL (WUS) is a homeodomain transcription factor vital for stem cell proliferation in plant meristems. In maize, ZmWUS1 is expressed in the inflorescence meristem, including the central zone reservoir of stem cells. ZmWUS1 overexpression in the Barren inflorescence3 (Bif3) mutant perturbs inflorescence development due to stem cell over-proliferation. RESULTS: Single-cell Assay for Transposase Accessible Chromatin sequencing (scATAC-seq) shows that Bif3 alters central zone chromatin accessibility compared to normal inflorescence meristems. The CAATAATGC motif, a known homeodomain recognition site, is enriched within regions with increased chromatin accessibility in Bif3, suggesting ZmWUS1 could function as a transcriptional activator in the central zone. This motif differs from the TGAATGAA motif identified by DNA Affinity Purification sequencing (DAP-seq) of ZmWUS1, which showed low enrichment in the central zone. Conversely, regions with decreased chromatin accessibility in Bif3 are instead adjacent to AUXIN RESPONSE FACTOR genes, suggesting possible reduced auxin signaling in the Bif3 central zone. CONCLUSIONS: This study characterized how Bif3 overexpression of ZmWUS1 influences chromatin accessibility in the central zone, reducing auxin signaling, while raising questions about differential ZmWUS1 motif usage in distinct cellular contexts.