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

Abstract

WUSCHEL (WUS) is transcription factor vital for stem cell proliferation in plant meristems. In maize, ZmWUS1 is expressed in the inflorescence meristem, including the central zone, the reservoir of stem cells. ZmWUS1 overexpression in the Barren inflorescence3 mutant leads to defects in inflorescence development. Here, single-cell ATAC-seq analysis shows that ZmWUS1 overexpression alters chromatin accessibility throughout the central zone. The CAATAATGC motif, a known homeodomain recognition site, is predominantly observed in the regions with increased chromatin accessibility suggesting ZmWUS1 is an activator in the central zone. Regions with decreased chromatin accessibility feature various motifs and are adjacent to AUXIN RESPONSE FACTOR genes, revealing negative regulation of auxin signaling in the central zone. DAP-seq of ZmWUS1 identified the TGAATGAA motif, abundant in epidermal accessible chromatin compared to the central zone. These findings highlight ZmWUS1s context-dependent mechanisms for stem cell maintenance in the inflorescence meristem.