An efficient DNA- and selectable-marker-free genome-editing system using zygotes in rice

Area of Science:

• Plant biotechnology
• Genome editing technologies
• Crop improvement strategies

Background:

• The CRISPR-Cas9 system enables targeted plant mutagenesis for breeding.
• Previous methods involved integrating Cas9-gRNA cassettes, leading to off-target effects and regulatory concerns.
• DNA-free methods using ribonucleoproteins (RNPs) in protoplasts or embryo cells have limitations in efficiency and applicability.

Discussion:

• This study introduces a novel genome editing system using direct delivery of Cas9-gRNA RNPs into plant zygotes.
• This approach bypasses the need for protoplast isolation or biolistic bombardment, overcoming limitations of previous DNA-free methods.
• The system was successfully applied to rice zygotes produced via in vitro fertilization, leading to mature, genome-edited plants.

Key Insights:

• Direct zygote transfection of Cas9-gRNA RNPs achieves efficient, DNA-free genome editing in plants.
• Regeneration of targeted mutant rice plants occurred at frequencies of 14-64% without selection agents.
• This method avoids foreign DNA integration, addressing regulatory concerns and off-target modification risks.

Outlook:

• This efficient system holds significant potential for accelerating crop improvement in rice and other essential crop species.
• Further research can explore the applicability of this zygote-based RNP delivery in a wider range of plant species.
• This technology could revolutionize the development of next-generation crops with desirable traits.