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

Area of Science:

• Plant developmental biology
• Molecular genetics
• Epigenetics

Background:

• WUSCHEL (WUS) is a key transcription factor regulating stem cell proliferation in plant meristems.
• In maize, ZmWUS1 is crucial for inflorescence meristem development and stem cell maintenance.
• The Barren inflorescence3 (Bif3) mutant exhibits abnormal inflorescence development due to ZmWUS1 overexpression and stem cell over-proliferation.

Purpose of the Study:

• To investigate the impact of ZmWUS1 overexpression in the Bif3 mutant on chromatin accessibility in the maize inflorescence meristem.
• To identify potential ZmWUS1 binding motifs and their role in regulating gene expression.
• To explore the relationship between ZmWUS1 activity, chromatin accessibility, and auxin signaling.

Main Methods:

• Single-cell Assay for Transposase Accessible Chromatin sequencing (scATAC-seq) to profile chromatin accessibility at a single-cell level.
• DNA Affinity Purification sequencing (DAP-seq) to identify ZmWUS1 DNA-binding motifs.
• Comparative analysis of chromatin accessibility patterns in wild-type and Bif3 mutant meristems.

Main Results:

• scATAC-seq revealed significant alterations in chromatin accessibility in the Bif3 mutant's central zone compared to wild-type.
• The CAATAATGC motif, a homeodomain recognition site, was enriched in accessible regions in Bif3, suggesting ZmWUS1 acts as a transcriptional activator.
• Regions with decreased accessibility in Bif3 were located near AUXIN RESPONSE FACTOR genes, indicating potential downregulation of auxin signaling.

Conclusions:

• Bif3-mediated ZmWUS1 overexpression alters chromatin accessibility and reduces auxin signaling in the maize inflorescence central zone.
• The study highlights potential differential usage of ZmWUS1 binding motifs in various cellular contexts.
• Findings raise questions about the precise mechanisms of ZmWUS1 regulation and its interplay with auxin pathways during plant development.