Precision Breeding for a Global Staple Food: A Systematic Review with a Strategic Framework for CRISPR-Cas...

Background: Rice is one of the world's main staple crops, and improving its productivity and resilience is important to achieving food security under varying climatic conditions. Objectives: This systematic review synthesizes the existing evidence on the application, technical limitations, and potential of the development of genome editing technologies (CRISPR-Cas) in rice (Oryza sativa L.), as well as presents a novel approach called the CRISPR Trait Prioritization and Readiness Framework (CTPRF). Methods: Peer-reviewed articles that reported applications of genome editing based on the CRISPR-Cas system in the genome of rice for trait improvement or functional genomics were identified through searches fromPubMed, Scopus, Web of Science, and Google Scholar with studies published between 2012 and 2025. Studies were screened on predefined inclusion criteria related to experimental validation, reporting of editing efficiency, and clear phenotypic results. Data on CRISPR systems, target genes, methods of delivery, traits modified, and phenotypic results were extracted and synthesized by comparative analysis. Results: A wide variety of different CRISPR systems have been used in rice, and our results indicate that NHEJ-mediated knockouts are effective in average genotypes with editing efficiencies in the range of 70-90%, but HDR and prime editing are still under 10%. The CTPRF is being introduced as a strategic decision support tool to evaluate traits from four dimensions: technical feasibility, phenotypic predictability, impact potential, and regulatory pathway. We use this framework for case studies in pioneering countries (USA, Japan, China) and show how it can be useful for guiding research investment and policy. Conclusions: CRISPR-Cas technologies have transformed rice breeding, but their introduction requires overcoming genotype-dependent barriers to transformation and negotiating patchwork regulatory environments. The CTPRF offers a roadmap for the acceleration of the development of climate-resilient and nutritious rice varieties for the action plan.