Researchers have successfully performed the first DNA-free gene editing on raspberry plants, marking a scientific advance that could eventually lead to improved berries without the regulatory complexities of traditional genetic modification.
The technique, described in a paper published in Frontiers in Genome Editing, uses molecular scissors called CRISPR to make precise cuts in raspberry genes, then relies on the plant’s natural repair mechanisms. Unlike conventional genetic engineering, no foreign DNA remains in the plant’s genome after editing. While regulatory frameworks for such “precision bred” crops are still evolving, early legislation in England suggests these plants may face fewer hurdles than traditional GMOs.
For raspberries, this could represent a major step forward. These berries present unique challenges for plant breeders because each seed produces a genetically different plant. Commercial growers rely on cloning techniques to maintain consistent berry quality, making traditional breeding extremely slow. Improvements that could take years through conventional methods might be achievable much faster through direct gene editing.
How Scientists Removed Cell Walls to Enable Raspberry Gene Editing
Led by Ryan Creeth, a PhD student at Cranfield University in England, researchers started with raspberry tissue cultures, then used enzymes to strip away the rigid cell walls, creating protoplasts. Without their protective barriers, these naked plant cells become permeable to gene-editing tools.
Scientists combined the protoplasts with pre-assembled CRISPR components, including Cas9 proteins and guide RNAs, along with chemicals that help the editing machinery penetrate cell membranes. After 24 hours, they extracted DNA and used sequencing techniques to confirm successful edits.
The team successfully modified a gene called phytoene desaturase with a 19% efficiency rate. That’s a notable improvement over the very low efficiencies reported in earlier Agrobacterium-based genetic modification attempts in raspberry. They also edited three other genes linked to fruit firmness and disease resistance, though with lower success rates.
Editing Success Varied Dramatically Between Gene Targets
The 19% editing efficiency represents progress over existing approaches and eliminates the years of backcrossing typically required to remove unwanted genetic material from conventionally modified plants.
However, editing efficiency varied dramatically depending on the target gene, ranging from 0.3% to 19%. This variation suggests each genetic target would need extensive optimization before achieving reliable results for practical applications.
Source material quality proved critical. Protoplasts from healthy, vigorous raspberry canes produced between 1 million and 12 million usable cells per milliliter, while poor-quality plants yielded far fewer. Researchers noted the best results came from bright green stems with deep red thorns and rapidly growing tissue cultures.
Will Consumers Be Eating Gene-Edited Raspberries Anytime Soon?
The biggest obstacle is regenerating whole plants from edited protoplasts. While previous research suggests raspberry protoplasts can potentially grow into complete plants, no one has demonstrated this capability with gene-edited cells. Without successful plant regeneration, the technique remains a laboratory proof-of-concept rather than a practical breeding tool.
Cost considerations also pose challenges. The study relied on expensive commercially synthesized CRISPR components, though researchers suggested costs could decrease if laboratories produce these tools internally once targets are validated.
The research does open possibilities for addressing long-standing raspberry problems. Enhanced disease resistance could reduce pesticide use, while improved fruit firmness could extend shelf life and reduce food waste. Both outcomes would benefit farmers, consumers, and the environment.
As the researchers noted in their paper, “To our knowledge, this study constitutes the first use of DNA-free genome editing in raspberry protoplast. This protocol provides a valuable platform for understanding gene function and facilitates the future development of precision breeding in this important soft fruit crop.”
The work represents an early step in precision agriculture for raspberries, a crop that has seen limited innovation due to complex genetics. If the remaining technical hurdles can be overcome, DNA-free editing could eventually enable rapid, targeted improvements throughout the raspberry industry.
Source : https://studyfinds.org/first-dna-free-gene-editing-raspberry-plants-crispr/
