Coffee plants can be propagated by grafting a shoot onto the rootstock of another plant
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The age-old technique of grafting plants may have a revolutionary application in modern gene editing, offering a solution for modifying plants that are traditionally challenging to edit through conventional methods.
According to Ugo Rogo from the University of Pisa in Italy, “It is still at the beginning stage, but this technique has great potential.” Enhancing the productivity and nutritional value of plants is crucial in mitigating the environmental impact of agriculture and addressing food scarcity issues as the global population expands and climate change threatens crop yields. The precision of CRISPR gene editing presents a promising avenue for achieving these goals.
Editing plant genes poses difficulties due to the rigid cell walls surrounding plant cells, a feature absent in animal cells. Traditional genetic engineering methods involve techniques like biolistics or the use of the microbe Agrobacterium to modify plant cells. However, these approaches are ineffective for many plants, especially trees, cocoa, coffee, sunflowers, cassava, and avocados.
Moreover, regulatory approval for genetically modified plants varies depending on the method used. While CRISPR-induced mutations are often deemed equivalent to natural mutations by regulators, biolistics and Agrobacterium may introduce unwanted DNA into plant genomes, necessitating stringent regulatory processes.
To address these challenges, researchers are exploring novel approaches to gene editing that are applicable to a wider range of plant species without introducing foreign DNA. One innovative method involves using viruses to deliver RNA encoding CRISPR components to plant cells. However, the large size of the Cas9 protein used in gene editing limits its delivery via viruses.
In 2023, Friedrich Kragler from the Max Planck Institute of Molecular Plant Physiology in Germany introduced a groundbreaking technique. By leveraging the ability of plant roots to transport specialized RNA molecules to shoots and leaves, Kragler’s team genetically engineered plants to produce RNA encoding essential CRISPR components. Grafting shoots from modified plants onto non-modified plants resulted in successful gene editing of shoots and seeds.
Rogo and his team recognize the immense potential of this approach and are advocating for its further development. By utilizing grafting, researchers can utilize the CRISPR system in tree species and plants like sunflowers that were previously resistant to gene editing techniques.
One significant advantage of grafting is the ability to graft distantly related plants together, enabling the transfer of gene editing capabilities across species. This opens up possibilities for engineering compatible rootstocks for gene editing in plants where direct modification is challenging.
By creating transgenic rootstocks that produce the necessary RNAs, researchers can facilitate gene editing in a wide range of plant varieties. This approach offers a cost-effective and sustainable solution for enhancing plant traits like disease resistance and productivity.
Looking ahead, researchers envision combining grafting with viral delivery systems to optimize gene editing efficiency. By using rootstocks for Cas9 delivery and viruses for guide RNA transmission, researchers can achieve precise gene edits across multiple plant species using a single rootstock.
Overall, the integration of grafting and gene editing holds immense promise for revolutionizing plant biotechnology and addressing global food security challenges. By harnessing the natural transport mechanisms of plants and leveraging innovative genetic engineering techniques, researchers are paving the way for a sustainable and efficient approach to enhancing crop traits and yields.
