Genome editing based trait improvement in crops: current perspective, challenges and opportunities

The exponentially increasing population poses a serious threat to global food security. Concurrently, the climate change condition also limits crop productivity by enhancing the effect of biotic and abiotic stressors. The traditional crop improvement programs are not enough to meet the food and nutritional requirements of such a progressive population. Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) based genome editing tool adopted from bacterial adaptive immune system against invading foreign DNA has demonstrated its tremendous potential in the sector of crop improvement. CRISPR/Cas-mediated targeting can activate, repress, or completely abolish the gene function. CRISPR/Cas-mediated interventions can produce biofortified crops by targeting negative regulators or activating positive regulators for nutrients. Thus, it can address nutritional security concerns. The advancement in CRISPR/Cas-mediated genome editing, encompassing base and prime editing has paved the way to modify an organism's genome in a predictable and precise manner. The use of morphogenetic regulators can omit the problem of tissue culture stages, which is one of the major bottlenecks in plant genome editing. CRISPR/Cas-based genome editing has been performed in many crop plants to induce biotic and abiotic stress tolerance, increase quality and nutritional values, enhance productivity, and prevent post-harvest losses. In this review article, we summarize the progress, challenges opportunities and regulatory landscape of genome editing for the improvement of various traits in crop plants.