Experimental tomato cultivation with vitamin D in England

Scientists at the John Innes Center in the UK used the Crispr / Cas9 genetic engineering technique to modify the tomatoes to enrich the fruit and leaves with vitamin D. The first field trials will begin in June. If the Brits relax the rules for new genetic engineering as planned, tomatoes could soon be on the market. Critics of genetic engineering doubt they can really provide people with vitamin D.

Tomatoes naturally contain very small amounts of 7-dehydrocholesterol. The substance is also called provitamin D3 because vitamin D3 develops from it when exposed to ultraviolet light. During research on the metabolic processes of tomatoes, scientists discovered that an enzyme converts 7-dehydrocholesterol into other plant substances, the esculeosides. They help the tomato fight parasites and pathogens. The John Innes Center (JIC) team, led by Professor Cathie Martin, has now used Crispr / Cas9 to silence the gene that produces this enzyme. As a result, 7-dehydrocholesterol accumulated in the leaves and fruits of the manipulated tomato plants, while the esculeoside content decreased significantly.

If the modified tomatoes were irradiated with UV light (which the sun must do outdoors), the 7-dehydrocholesterol present in the fruit was converted into vitamin D3. In a study published in the journal Nature Plants, the JIC researchers calculated that one would consume as much vitamin D with such a tomato as with the consumption of two eggs or 28 grams of tuna. Additionally, the vitamin D3 in the leaves could be made into food supplements. The tomato is therefore suitable to compensate for a low intake of vitamin D, which, according to the study, affects one billion people. Other closely related plants that share the same metabolic pathway, such as eggplant, potatoes and peppers, could also accumulate vitamin D using this method, the JIC press release states. Especially during the corona pandemic, it became clear how important a good level of vitamin D is for health.

Turning off the gene did not have a negative effect on plant growth, development and yield, according to the greenhouse study experience. Whether this also applies to the field remains to be seen. The Munich Testbiotech Institute warns that genetic engineering intervention in their protective mechanism could make tomatoes more susceptible to disease and pest infestations. Other interactions with the environment should also be investigated. In the case of the tomatoes themselves, it should be checked whether the intervention has inadvertently changed the ingredients or interrupted other metabolic pathways. Finally, Testbiotech points out that the concentration of vitamin D in tomatoes can vary greatly depending on the variety and environmental conditions. In the journal Nature, scientists comment that more research is needed on how stable the vitamin is in tomatoes when stored or processed. It also needs to be clarified how well the human body can absorb the vitamin from tomatoes. It is impossible to reliably dose this way, writes Testbiotech.

In order to promptly identify possible risks to health or the environment, the institute asks to examine in detail the risks of these genome-modified plants. Liz O’Neill, CEO of the anti-GMO organization GM Freeze, says the new tomato is simply superfluous: “Supermarket shelves are already full of excellent sources of vitamin D: from fatty fish, eggs and red meat to fortified cereals. and a variety of dietary supplements “. Adding a “dark tomato” will not solve the vitamin D deficiency problem because poor nutrition is a consequence of poverty and a broken food system. “We need a system change, not genetically engineered ketchup,” O’Neill said. [lf/vef]

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