Genome-Editing Technologies in Crop Improvement

Global climate change, together with harmful biotic and abiotic factors, is limiting agricultural yields, rendering it challenging to meet the rising need for food supply on a global scale. The development of hybrid cultivars with greater agricultural output was facilitated by the use of applied genetics for improving crops. However, it becomes a challenge for crop breeders to develop new varieties using current gene pools. The time needed to develop novel varieties of crops with the necessary agronomic features limits the utilization of traditional breeding methods. This is dependent not only on the amount of time required for growing in a particular season and the time needed to reach maturity but also on the usage of numerous cycles and phases of breeding processes, which involve crossing, selection, and testing. Furthermore, conventional physical and chemical mutagenesis approaches do not permit targeted genomic effects. Genome-editing approaches have evolved as significant tools for accurately altering genomes at specific locations. Genome-editing tools cause breaks in double-strand breaks (DSBs) at a target site and are repaired either through homologous recombination (HDR) or nonhomologous end joining (NHEJ) pathways. The amendment of the targeted genome at a precise location and the exclusion of foreign deoxyribonucleic acid (DNA) in crops that are genomically edited are some of the noteworthy properties of genome-editing tools, leading to their wide implementation in crop improvement. This chapter aims to highlight different genome-editing techniques, like zinc-finger nucleases (ZFNs), clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated (Cas) protein systems, and transcription activator-like effector nucleases (TALENs), followed by issues and challenges, and their applications in crop improvement.