Genome Editing with Engineered Nucleases in Economically Important Animals and Plants: State of the Art in the Research Pipeline

Kateřina Demnerová,Gerard Kerins,Tereza Sovová,Jaroslava Ovesná

doi:10.21775/cimb.021.041

Abstract

After induced mutagenesis and transgenesis, genome editing is the next step in the development of breeding techniques. Genome editing using site-directed nucleases - including meganucleases, zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the CRISPR/Cas9 system - is based on the mechanism of double strand breaks. The nuclease is directed to cleave the DNA at a specific place of the genome which is then repaired by natural repair mechanisms. Changes are introduced during the repair that are either accidental or can be targeted if a DNA template with the desirable sequence is provided. These techniques allow making virtually any change to the genome including specific DNA sequence changes, gene insertion, replacements or deletions with unprecedented precision and specificity while being less laborious and more straightforward compared to traditional breeding techniques or transgenesis. Therefore, the research in this field is developing quickly and, apart from model species, multiple studies have focused on economically important species and agronomically important traits that were the key subjects of this review. In plants, studies have been undertaken on disease resistance, herbicide tolerance, nutrient metabolism and nutritional value. In animals, the studies have mainly focused on disease resistance, meat production and allergenicity of milk. However, none of the promising studies has led to commercialization despite several patent applications. The uncertain legal status of genome-editing methods is one of the reasons for poor commercial development, as it is not clear whether the products would fall under the GMO regulation. We believe this issue should be clarified soon in order to allow promising methods to reach their full potential.

Highlights

The effort to improve animals and plants used for food production is as old as agriculture itself
The genetic basis of domesticated species has been changed by selecting the best progeny to improve desirable characteristics, such as yield and disease resistance, in subsequent generations
With scientific and technological development, innovative techniques were increasingly applied in the breeding process such as induced mutagenesis or tissue cultures (Fichtner et al, 2014; Puchta and Fauser, 2014; Rinaldo and Ayliffe, 2015)

Summary

Introduction

The effort to improve animals and plants used for food production is as old as agriculture itself. There has been a need for different genome-modifying techniques that would allow a more precise and speedy generation of new organisms, and that would at the same time require a less extensive changes to the DNA (Bruce et al, 2013; Puchta and Fauser, 2014). Compared to ZFNs, the design is more straightforward, and longer recognition sites increase the specificity of TALENs making it less prone to off-target mutations and less likely to cause deleterious effects (Puchta and Fauser, 2014; Petersen and Niemann, 2015b). It consists of guide RNAs that direct a nuclease, e.g. Cas, which is utilised by bacteria such as Streptococcus pyogenes in their adaptive immunity systems to recognize and cleave a specific site in the target DNA (Puchta and Fauser, 2014; Rinaldo and Ayliffe, 2015). The cultivation of diseaseresistant plants has the potential to reduce the "44

Gene expression control rapeseed kasii oil content

Findings

Type of Species