The use of CRISPR/Cas9 as antiviral approach in crop plants can lead to the emergence of new viral variants resistant to CRISPR/Cas9

Researchers from ETH Zurich, the University of Alberta and the University of Liège (Prof. Hervé Vanderschuren, Director of the Plant Genetics Lab at Gembloux Agro-Bio Tech) are publishing new results on the CRISPR-Cas9 genetic editing technology in the prestigious scientific journal Genome Biology (1) this week.

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or the first time, these results show that the use of the CRISPR-Cas9 technology to develop virus resistance in plants could, on the contrary, accelerate, under certain conditions, the evolution towards variants of viruses that are immune to CRISPR treatments. These are important results for the optimization, diversification and safe use of CRISPR technology, which remains promising for the development of improved food crops.

Geminiviruses cause harmful diseases in several important food crop species. Little progress has been made in the development of crop varieties resistant to these very diverse DNA viruses. CRISPR-Cas9 technology has recently been used to edit the genome of these plants and provide them with immunity to geminiviruses.

In this study, CRISPR-case9 was used in cassava plants to develop resistance to the African cassava mosaic virus, a member of a large and widespread family of DNA viruses pathogenic to plants.

The results obtained by the researchers show that CRISPR does not provide effective virus resistance in this case after inoculation under glasshouse conditions. In addition, they find that between 33 and 48% of modified virus genomes produce a mononucleotide mutation that results in resistance to the use of CRISPR-Cas9.

For Prof. Hervé Vanderschuren "the risks described in this research concern a small subset of CRISPR-Cas9-based applications and not the conventional uses of CRISPR-Cas9, as we have already successfully used them in my laboratory for improving the genetic characteristics of crop plants."(1)

Professor Hervé Vanderschuren's team has also recently developed technologies for robust assessment of plant resistance to viruses under field conditions.(2) "With this new study, we are demonstrating the need for a robust evaluation of these technologies to ensure the safe deployment of improved crop varieties that have the potential to increase global food security, as we recently presented in a Perspective article in Science magazine," concludes Professor Hervé Vanderschuren.(3)

CRISPR-Cas9 is a recently discovered new technique that uses an enzyme and a specific guide RNA to cut the genome at a specific location, easily and quickly. The prospects for this DNA sequence modification technique (genome editing) are promising, particularly in gene therapy.

References

(1) Linking CRISPR-Cas9 interference in cassava to the evolution of editing-resistant geminiviruses, Genome Biology

(2) Accelerated ex situ breeding of GBSS- and PTST1-edited cassava for modified starch, Bull et al., Science Advances, 2018

(3) A new full-length circular DNA sequencing method for viral-sized genomes reveals that RNAi transgenic plants provoke a shift in geminivirus populations in the field, Nucleic Acids Research, Volume 47, Issue 2, 25 January 2019.
Read also : A new method for the high throughput sequencing of full virus genomes, Press Release ULiège

(4) Crops improved to help reduce hunger in the world, Press Release ULiège

Contact

Prof. Hervé Vanderschuren, Plant Genetics Lab, Gembloux Agro-Bio Tech (ULiège)

+32 81 62 25 71 I +32 478 41 33 13 I E-MAIL