eLife Assessment
This study employs state-of-the-art quantitative imaging and genomics approaches to address a fundamental question regarding the establishment of Polycomb domains during Drosophila embryogenesis. The authors identify the maternal-to-zygotic transition, rather than earlier developmental stages, as the critical window for Polycomb domain establishment, providing significant clarification of the timing of this process and they further investigate the roles of Zelda and GAGA factor, demonstrating that Zelda, but not GAGA factor, contributes to Polycomb domain establishment. Overall, the conclusions are well supported by the experimental evidence presented. These compelling findings advance our understanding of how Polycomb domains are established during early embryogenesis and have broad implications for chromatin regulation and developmental biology.