Gene targeting: development of novel systems for genome engineering in plants.

Gene targeting has long been a major goal for researchers interested in the production of transgenic plants with stable and predictable patterns of gene expression. Unfortunately gene targeting in plants has been extremely difficult. We review the current status of gene targeting in plants along with recent breakthroughs in novel approaches to the use of site-specific recombinases, mutant host plants, and homologous recombination techniques. While the new gene targeting technologies are presently being used in model plants such as Arabidopsis, rice and tobacco, the new findings bode well for gene targeting technologies becoming available for economically important crop and horticultural plants.