CRISPR-Cas Technology: A Genome-Editing Powerhouse for Molecular Plant Breeding

Global human population is growing rapidly. The latest world population projections indicate human population will reach ten billion in the year 2055 (The World Bank). Simultaneously limited cultivable land, climate change, and plant diseases greatly impede the crop yield improvement necessary to feed the growing population. Breeders and farmers face a grand challenge in sustaining production to accommodate the population numbers in a race against time. Precision and rapid breeding are effective ways to tackle this great challenge (Hickey et al., Nat Biotechnol 37:744-754, 2019). Conventional genetic-engineering (GE) transgenic technology is an important approach in modern plant breeding, and several transgenic plant varieties with improved yields, disease-resistance, and drought-tolerance have been developed. However, the process of producing them is extremely laborious and time-consuming. These GE products also face a lengthy government regulation process before their release and commercialization. They also have a history of being poorly received by consumers. Novel genome-editing technology, especially the CRISPR-Cas-based system, has revolutionized bioscience fields from medicine to agriculture. CRISPR-Cas system displays several advantages over earlier gene-targeting technologies, such as TALEN and ZFN. Its simple design provides precise, targeted editing of living cell genomes with unparalleled editing efficiency and lower costs than other technologies. With these considerations, this review describes the implications of genome-editing tools in plant breeding and crop improvement.