Emerging applications of CRISPR-Cas9 genome editing in horticultural crop improvement

CRISPR/Cas-based genome editing has emerged as a powerful and precise tool for crop improvement, enabling targeted modification of genes associated with agriculturally important traits. In horticultural crops, CRISPR technologies have accelerated the improvement of disease resistance, abiotic stress tolerance, yield, nutritional quality, shelf life, flowering behavior, and ornamental characteristics. Among available genome-editing platforms, CRISPR/Cas9 is the most widely utilized because of its simplicity, efficiency, and versatility. The technology enables precise genome modification through targeted DNA cleavage followed by endogenous repair mechanisms, facilitating gene knockout, insertion, or sequence alteration. Recent advances in genome editing have significantly expanded its applications in vegetable, fruit, and ornamental crops. Successful modifications targeting genes associated with stress tolerance, fruit ripening, pigment biosynthesis, flowering regulation, and pathogen resistance demonstrate the enormous potential of CRISPR-mediated breeding for horticultural improvement. However, several challenges, including low transformation efficiency, genotype-dependent regeneration, prolonged juvenile phases, polyploidy, and regulatory concerns, continue to limit its broader application in many horticultural species. This review summarizes recent progress in CRISPR/Cas-mediated genome editing in horticultural crops, including strategies for guide RNA design, transformation, regeneration, development of transgene-free plants, and regulatory considerations. Furthermore, emerging advances such as precision editing technologies and improved delivery systems are discussed as promising approaches for enhancing editing efficiency and expanding future applications. Overall, CRISPR/Cas technologies hold substantial potential for accelerating the development of climate-resilient, high-quality, and nutritionally improved horticultural crops.