Protocol for precision engineering of plant gene loci by homologous recombination cloning in Escherichia coli. Includes: Key steps in the EL250 RED-HR locus rescue and engineering procedure; Primer design and plasmid constructs; AtSTM gap-repair construct; Targeting construct backbone; Preparation of electrocompetent EL250 cells; Transformation of BAC F24o1 and induction of recombinogenic function in EL250; AtSTM locus rescue from BAC F24o1 by gap-repair HR.