Recently developed methods for genome editing, representing a major breakthrough in the field of genetic engineering, will enable researchers to produce transgenic plants in a more convenient and safer way. Double-strand breaks (DSBs) are triggered by synthetic nucleases that later induce DNA repair mechanisms known as nonhomologous-end joining (NHEJ) or homology-directed repair (HDR) in the presence of a donor DNA. Gene targeting (GT) was earlier demonstrated in rice and maize genomes by exploiting several genes (Acetohydroxyacid synthase, waxy, ALS, OS11N3 etc.), while zinc finger nucleases (ZFNs) were used to modify IPK1 gene in maize. Clustered regularly interspaced short palindromic repeats (CRISPR-CAS) system has been shown to be efficient for targeted mutagenesis in wheat that has a hexaploid complex genome, rice, maize, and recently in barley. The CRISPR system is considered as advantageous over previous approaches due to its easy use and efficiency, however, needs to be improved for high off-target effects.
Part of the book: Genetic Engineering