Crop improvement aims at substantial enhancements in the quality, yield and stress resistance of crops to meet the increasing food demand of growing world population. Targeted genome modification of crop plants is one of the ways to achieve this. This technology supersedes conventional methods limited by the inefficiencies of random mutation, accuracy and stability. It employs site-directed nucleases to create breaks at specific points in the target genome for desired alteration with high-precision. There are four nucleases namely, LAGLIDADG homing endonucleases (LHEs), zinc finger nucleases (ZFNs), &nbsp;transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR) nucleases out of which three, ZFNs, TALENs and CRISPR have been highly studied and evaluated in various crop systems for economic trait. Potency of engineered nucleases lies in their efficacy to bring desired modification in diploid as well as in polyploid plant genomes. Modifications using genome editing are similar to natural or conventional method like induced mutations and are foreseen to waive regulatory actions as applicable to genetically modified organisms. This review seeks to emphasize on the employment of engineered nucleases in various crops plants till date.

Genome modifications in crops employing engineered nucleases

For a number of decades, attempts have been made to successfully produce transgenic animals which have numerous applications in the biotechnology industry with the foremost emphasis on production of monoclonal antibodies and recombinant proteins of human welfare. Different techniques are adopted in order to produce transgenic farm animals which could be further used as bioreactors. The most common traditional transgenesis technique employed is Somatic Cell Nuclear Transfer (SCNT) using genetically modified somatic cells or stem cells as nuclear donors. This review article summarizes the merits and demerits of the techniques currently used to produce transgenic livestock with major emphasis on somatic cell nuclear transfer. In the end, a brief discussion is done about the novel methods adopted to produce transgenic animals like Zinc Finger Nucleases (ZFN), Transcription Activator-like Effector Nuclease (TALEN) and Clustered regularly interspaced short palindromic repeats (CRISPR). It is expected that the new techniques developed would overcome the problems faced with existing traditional transgenesis methods.&nbsp;

Genome modifications in crops employing engineered nucleases

Transgenesis in farm animals-A review