CRISPR/CAS-MEDIATED GENOME EDITING IN RICE IMPROVEMENT: TOOLS, APPLICATIONS, ADVANCES AND CHALLENGES

Abstract

Rice (Oryza sativa L.) is a major staple crop that plays a crucial role in global food and nutritional security. However, increasing population pressure, climate change, emerging biotic and abiotic stresses, and limitations of conventional breeding necessitate the development of improved rice varieties with enhanced productivity, quality and resilience. Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein (Cas)-mediated genome editing have emerged as powerful tools for precise and targeted genetic improvement in rice. This review highlights the molecular basis, evolution and technological advancements of CRISPR/Cas genome-editing systems, with particular emphasis on Cas9, Cas12a, base editing and prime editing. Different delivery approaches, including Agrobacterium-mediated transformation, particle bombardment, protoplast-based transformation and ribonucleoprotein delivery, are discussed. The applications of genome editing in rice improvement are comprehensively examined, covering yield-related traits, plant architecture, grain size and quality, nutritional biofortification, resistance to bacterial and fungal diseases, tolerance to abiotic stresses, flowering time, root architecture and nutrient-use efficiency. Furthermore, multiplex genome editing offers opportunities for simultaneous modification of multiple genes and complex traits, thereby accelerating the development of improved rice cultivars. Despite these advances, challenges associated with transformation efficiency, genotype dependency, off-target effects, regeneration, regulatory frameworks and field-level validation remain. Integrating CRISPR/Cas technology with genomics, molecular breeding, genomic selection and advanced phenotyping could further enhance the precision and efficiency of rice improvement. Overall, CRISPR/Cas-mediated genome editing represents a promising strategy for developing high-yielding, climate-resilient, disease-resistant and nutritionally superior rice varieties to support sustainable agriculture and global food security.