Genome editing: Advances and prospects

There is an urgent need to develop quality crop with improved productivity and wider tolerance to the environmental (biotic and abiotic) stresses for addressing different issues including global water crisis, food security, and climate change effect on agriculture. Traditional lengthy procedures for crop improvement including classical breeding and random mutagenesis will not be able to fulfill growing crop demand in near future. Gene targeting technology is a powerful transformative procedure that permits accurate genetic modification in any genome which relies on a variety of molecular editors. Formation of directed DNA cleavage by ZFNs, TALENs, and CRISPR/Cas9, followed by restoration via the DNA repair system either by NHEJ (non-homologous end joining) or by HDR (homology directed recombination), provides a useful insight of gene function and trait modification. In this chapter, we have described the four available types of genome editing tools; meganucleases, ZFNs, TALENs, and CRISPR systems, and discussed their revolutionary applications in precision molecular breeding and functional genomics research of crops. Furthermore, specific challenges in the plant genome editing and prospects were also reviewed.