Chinese researchers have pioneered novel genome editing platforms termed Programmable Chromosome Engineering (PCE), achieving unprecedented megabase-scale DNA manipulations in eukaryotic cells. By overcoming challenges associated with Cre-Lox recombinase reversibility and scar formation, the team engineered asymmetric Lox sites, enhanced recombinase efficacy using AI-guided protein engineering, and developed scarless editing via re-prime editing guided by specific pegRNAs. These innovations herald transformative capabilities in chromosome engineering, with broad applications across plant and animal biotechnology sectors.