Establishing a cutting-edge protoplast technology platform for applying new genomic techniques in Cichorium spp

Abstract

Genome editing technologies, especially those based on the CRISPR/Cas9 system, have revolutionized crop breeding by enabling precise genetic modifications. Specifically, delivering preassembled ribonucleoprotein (RNP) complexes—consisting of the Cas9 endonuclease coupled to specific single guide RNAs (sgRNAs)—into protoplasts offers an effective DNA-free method that prevents the integration of foreign genetic material. Despite the availability of detailed protocols, establishing a standardized and efficient in vitro regeneration procedure—from protoplast isolation to whole plant regeneration—remains challenging due to significant variability in regeneration efficiency across different varieties and biotypes. Therefore, optimizing each step is essential to maximize the recovery of successful edited plants. In this study, we developed an efficient protocol for regenerating whole plants from protoplasts isolated from 12 representative Italian varieties of chicory and endive. We focused on leaf chicory and endive biotypes with high horticultural value, including Radicchio types, which are important targets for quality improvement. Our optimized platform supports protoplast isolation, PEG-mediated transfection, and plant regeneration, demonstrating promising potential for future genome editing applications. Notably, the high responsiveness of protoplasts to PEG-mediated transfection suggests that coupling this method with our regeneration procedure could facilitate the use of advanced biotechnological strategies. The combination of high transient transformation efficiency, versatile encapsulation techniques, and successful plant regeneration establishes chicory and endive as promising candidates for DNA-free genome editing via protoplasts, providing a technically precise approach with reduced environmental and economic impacts compared to conventional breeding methods.