CRISPR-Based Tools for Crop Improvement: Understanding the Plant–Pathogen Interaction

Abstract

To deal with the growing world population, it has become necessary to increase the production and productivity of crop plants by minimizing losses caused by abiotic and biotic stresses. The increasing incidence of susceptibility of plants to infectious diseases makes it imperative to adopt new techniques that provide better resistance against pathogens. Conventional/molecular plant breeding and genetic modifications have been widely used to improve crop yield, quality, and architecture, and plants’ ability to resist diseases. However, limitations in resources and time, and the need for more specific targeting, have led to the use of a new avenue of targeted genome engineering. Advances in genomics have led to identification of a plethora of candidates suitable for genome modifications to engineer plant resistance against phytopathogens. However, off-target effects and regulatory issues associated with overexpression/underexpression via genome engineering greatly limit their applicability. A burst of advancements in genome-editing tools offers a new horizon to tackle these issues. Among various genome-editing tools, sequence-specific nucleases (SSNs) are proving to be more precise, more efficient, and less time consuming in altering key players for increasing plant immunity, and the CRISPR/Cas9 [clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9] system seems to be the most effective SSN. The CRISPR/Cas9 system has applications in various crop plants, ranging from single to multigene resistance against a range of pathogens. Recent advancements and refinements in CRISPR/Cas9 to effect targeted base editing offer further advantages by substantially reducing off-target effects, offering great promise in engineering of stress-resilient crop plants.