An Overview of Tools for Genome Editing: ZFNs, Mega Nucleases, and TALENs
Lekha Bhagtaney, Priya Sundarrajan
Abstract
Targeted gene modification has facilitated the alteration of genomes by the introduction of new genes or correction of faulty genes and exploration of gene functions. Thereby rendering targeted genome editing a powerful tool in genetics. The phenomenon of random mutagenesis occurs naturally in organisms leading to genome modifications. The technique of genome editing has progressed from the use of mutagens (physical or chemical agents) that can alter sequences of DNA to well-engineered biological tools that can generate gene knock-in and knock-out. Zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), mega nucleases, and clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) are some of these biological tools. Such multifaceted genome editing tools enable researchers to introduce modifications in an economic and rapid manner. These types of alterations of the genome that are sequence-specific can be 38reproduced in a wide range of organisms and cell types. Since its application is diverse across many fields of study, important scientific revolutions have been observed in areas like agriculture, human gene therapy and synthetic biology. Specifically in plants, these tools have contributed in discovery of new traits and also in the development of plants with increased crop yields and resistance to biotic and abiotic stresses. The following chapter will discuss the functioning, delivery methods, and applications of the genome editing tools ZFNs, mega nucleases, and TALENs in depth. We will also discuss the possible harmful effects or non-target effects of these tools and the controls in place for prevention of these effects. The present-day applications of genome editing pose a risk to clinical therapies and the safety of the food supply worldwide. A brief discussion on the challenges of genome editing will also be covered in this chapter.