Chinese researchers led by Professor Gao Caixia developed programmable chromosome engineering (PCE) systems achieving precision editing at megabase scale in eukaryotic cells. Their innovations include asymmetric Lox sites to limit reversible recombination, AiCErec protein engineering to enhance Cre recombinase activity, and a scarless editing strategy employing prime editors to remove residual Lox sites. This platform enables advanced genome manipulations with applications spanning plant and animal genetics and bioengineering.