Chapter 19 - Targeted Genome Editing for Crop Improvement in Post Genome-Sequencing Era

Abstract

Crop improvement is essentially required to provide food security and better nutrition globally for human beings. Plant breeders are utilizing both conventional and modern breeding techniques to increase crop production and quality. Though in the genome-sequencing era, marker-assisted selection-based breeding reduced timespan required for developing new plant variety from ~25 to ~7 years. But plant breeders are still looking for appropriate molecular method to quickly and precisely improve specific traits in plants. Recently discovered genome editing methods have revolutionized available technology for crop improvements. Genome editing is a tool of genetic engineering, which using engineered nucleases edits DNA of an organism. In editing, DNA is inserted, deleted, or replaced in the genome using engineered or designer nucleases. These nucleases create site-specific double-strand breaks (DSBs) at precise locations in the genome. The induced DSBs are repaired through more frequent nonhomologous end joining or less frequent homologous recombination, resulting in targeted mutations. The most common used engineered nucleases include meganucleases, zinc-finger nucleases, transcription activator-like effector nucleases, and clustered regulatory interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9). Targeted genome editing is the emerging technology that has wide applications in targeted gene mutation, creating chromosome rearrangement, gene function, SNP determination, and evolutionary studies in different organisms including plants, animals, and insects. Therefore, genome editing technology is a very prevailing technique that can be used toward fulfilling the demand of increasing food supply. Additionally, it is also a very effective technique in improving the nutritional value of crops, producing pest-resistant, abiotic stress-resistant, herbicide-resistant, and disease-free crops. In this chapter, we will broadly discuss the principles of the different techniques of genome editing and their applications in crop improvements.