Editing the RR-TZF Gene Subfamily in Rice Uncovers Potential Risks of CRISPR/Cas9 for Targeted Genetic Modification

Area of Science:

• Agricultural Science
• Genetics
• Biotechnology

Background:

• The CRISPR/Cas9 system is a revolutionary gene-editing tool with significant potential for improving crop productivity.
• Enhancing rice productivity through precise genetic modification is a key goal in agricultural research.

Purpose of the Study:

• To evaluate the efficiency and outcomes of CRISPR/Cas9-mediated editing of eight RR-TZF genes in japonica rice (Nipponbare).
• To investigate potential off-target mutations and inheritable mutagenicity in gene-edited rice.
• To analyze the phenotypic variations in homozygous mutants for improved rice trait evaluation.

Main Methods:

• CRISPR/Cas9 technology was employed to edit eight RR-TZF genes in japonica rice.
• High-throughput sequencing was used to confirm gene edits and analyze mutation types (insertions, deletions).
• Off-target analysis was performed on predicted sites, and progeny were analyzed for inheritable mutations and phenotypic traits.

Main Results:

• A high editing efficiency of 73.8% was achieved for the eight RR-TZF genes.
• Predominant mutations included short insertions/deletions and multi-base deletions near PAM sequences.
• Off-target mutations were detected in 5 of 31 predicted sites, and inheritable mutagenicity was observed in progeny.
• Phenotypic analysis revealed diverse agronomic traits among homozygous mutants, even for edits within the same gene.

Conclusions:

• CRISPR/Cas9 is effective for editing multiple genes in rice, but careful gRNA design is needed to minimize off-target effects.
• Inheritable mutagenicity necessitates backcrossing to ensure accurate phenotypic assessment and trait evaluation in gene-edited rice.
• This study provides valuable insights into CRISPR/Cas9 precision and its application in rice improvement strategies.