Genome Modification: Methods and Applications

Genetic modification of crops was first subjected to criticism, with claims that it was unnatural or even dangerous, and was dubbed “Frankenstein crops.” At that time, the word “Frankenstein” symbolized things that are unnatural or tampered with. However, at the same time, ancient humans were working to alter the genome to produce crops that were qualitatively and quantitatively better. Genome alteration was first associated with basic selective breeding techniques, but more recently, it has been sped up through modern methods that now speed up the process in an accurate and regulated manner. These modern techniques that enhance genomic modifications are crucial to meet global crop demands, as Tilman et al. (2011) speculate that, with an increasing population, the need for crop production might double by 2050. While the annual growth rate of major crops recorded in 2013 was wheat 0.9%, rice 1.0%, soybean 1.3%, and maize 1.6% (Ray et al. 2013). Factors such as reduced arable land, water scarcity, climate change, and rising biofuel consumption may hinder future crop production. Apart from crop yield, the development of new, better-performing varieties, good in terms of traits, nutrition, stress tolerance, disease resistance, and with less input requirements is also the choice of the era. However, traditional breeding methods to improve crops mainly rely on spontaneous genetic variation or on chemical and physical mutagenesis agents, and may use T-DNA insertional mutagenesis or transposon tagging techniques (Songstad et al. 2017) as natural genetic modification and artificial mutagenesis are limited by their random nature, low efficacy, and time- and labor-intensive nature. While gene targeting via homologous recombination allows precise mutation, its integration frequency is low and limited to a few crops (Puchta and Fauser 2013). In addition, genome editing techniques are revolutionizing crop improvement with high efficiency. The edited crops are not only transgene-free but also indistinguishable from those obtained from traditional techniques (Songstad et al. 2017).