A synthetic guide RNA scaffold enhanced CRISPR/Cas9 editing efficiency in plants across multiple gene targets

CRISPR/Cas9 mediated genome editing is a highly powerful and versatile tool for accelerating crop improvement. The editing efficiency of CRISPR/Cas9 system in planta has been highly variable owing to the variable binding affinity between native CRISPR RNA and Cas9 protein in vivo. In plant systems, systematic, large-scale engineering and benchmarking of guide RNA (gRNA) scaffold variants is still relatively limited compared with work in mammalian systems, despite several important studies demonstrating that scaffold and expression-cassette engineering can substantially improve CRISPR/Cas9 efficacy. Current study addresses the limitations of commonly used gRNA scaffold architecture by incorporating a stabilized stem-loop RAR (tetra loop) extension and a transcription-termination site mutation, resulting in improved RNA folding, increased Cas9 binding affinity, and enhanced in vivo editing outcomes. The synthesized scaffold boosted CRISPR/Cas9 efficiency in monocot or dicot plants across the 19 diverse target sites in Arabidopsis, rice and tomato. Furthermore, the synthetic scaffold is compatible with multiplex genome editing architectures, including polycistronic tRNA-gRNA (PTG) expression systems, enabling efficient simultaneous targeting of multiple genomic loci. The findings of this study have broad applications in precision plant breeding, functional genomics, and agricultural biotechnology, facilitating reliable gene modification across diverse plant species and transformation platforms.