Abstract: Methods for evolving recombinase protein homologues and RecA/VirE2 fusion proteins which complement VirE2 deficient Agrobacterium are provided. The use of recombinase protein homologues and RecA/VirE2 fusion proteins in the context of Agrobacterium mediated transformation are provided. Methods for producing transgenic organisms by homologous recombination using evolved recombinase proteins and Agrobacterium strains which express recombinase protein homologues or RecA/VirE2 fusion proteins are provided. Transgenic cells and organisms which have integrated an exogenous DNA sequence into a predetermined site in their genome are provided.