The SAS Chromatin-Remodeling Complex Mediates Inflorescence-Specific Chromatin Accessibility for Transcription Factor Binding

While the role of transcription factors in flower development is well understood, the impact of chromatin remodeling on this process remains largely unclear. We conducted a comprehensive analysis to investigate the coordination of the SAS, BAS, and MAS-type SWI/SNF chromatin-remodeling complexes with transcription factors to regulate chromatin accessibility and gene transcription during flower development in Arabidopsis thaliana . Our findings indicate that the SAS complex binds to numerous genes related to flower development and is responsible for establishing chromatin accessibility of these genes during flower development. In contrast, the BAS and MAS complexes exhibit minimal involvement in regulating the accessibility of these genes. The SAS-bound genomic regions and the SAS-dependent accessible regions are enriched with sites occupied by multiple MADS family transcription factors involved in flower development. Furthermore, we found that the SAS-dependent accessibility is indispensable for the genomic binding of the MADS transcription factor AP1 at these regions. This study highlights the dynamic role of the SAS complex in modulating the genomic binding of transcription factors during plant development. One-sentence summary The SAS-type SWI/SNF complex regulates Inflorescence-specific chromatin accessibility at distal promoter and upstream intergenic regions, thereby facilitating the binding of transcription factors involved in flower development.