Reforming cotton genes: from elucidation of DNA structure to genome editing

Cotton is an essential fiber producing crop in the world. It also supports additional industries by providing high quality oil and protein in the form of cottonseed cake. Currently, there is an urgent need to increase lint yield, fiber quality, and resistance to biotic and abiotic stresses due to rising pressure from a global population and possible supply shortages from the effects of erratic climate changes. Classic plant breeding and transgenic strategies need more genetic breakthroughs to support the increasing pressure for fiber quantity and quality. A potential for rapid increases in crop improvement is in various state-of-the-art gene editing technologies. Genetic research in simple micro-organisms revealed novel enzymes involved in natural sequence editing in cells, and they were successfully applied to gene editing in model plants through a system called clustered regularly interspaced short palindromic repeats-Cas9 (CRISPR-Cas9). This and other enzymatic systems are heralded as providing numerous possibilities for creating genetic variation for crop breeders. However, gene editing in agriculture is most effective when focused on achieving transmissible changes by inducing targeted mutations in genes involved in yield or quality attributes. The newly emerged CRISPR-Cas tools should accelerate future research in cotton breeding because they can be utilized efficiently for gene editing without the need for foreign gene insertion. Gene editing with CRISPR-Cas is achieved through the modification of gene regulatory mechanisms, enzymatic activities, and epigenetic factors as well as insect/pest gene drive technology, RNA targeting, and, more recently, single base and prime editing.