High effi cient genome modifi cation by designed zinc finger nuclease

Abstract

Zinc fi nger nucleases (ZFNs) are engineered artifi cial nucleases for inducing site-specifi c DNA double-strand breaks (DSBs) at the genomic loci of interest. There are two major DNA repair mechanisms in plant cells: nonhomologous end joining (NHEJ) and homologous recombination (HR). Repair of the DNA DSBs can lead to different genome modifi cations, such as targeted mutagenesis or chromosomal deletions by NHEJ, and gene targeting by HR. Thanks to the recent improvement on ZFN-engineering platforms, diverse ZFN-mediated genome modifi cations have been achieved in different plant species, such as Arabidopsis, tobacco, petunia, maize, and soybean. The frequencies of ZFN-mediated genome modifi cations are typically high in somatic cells, but quite low in germinal cells. In order to fully empower ZFNs in plant genome engineering, the challenges such as low germinal transmission frequencies and cellular cytotoxicity will need to be addressed in the near future.