Scientists have created genetically modified tomatoes, each of which contains as much provitamin D3 – a precursor of vitamin D – as two eggs or one tablespoon of tuna.
Outdoor trials of tomatoes are expected to begin in the UK next month and, if successful, could provide an important new dietary source of vitamin D.
Approximately 13-19% of Britons have low levels of vitamin D, which is needed to maintain healthy bones, teeth and muscles. Our main source of this nutrient comes from exposing our skin to sunlight, which converts provitamin D3 into an active form of vitamin D that our body can use.
However, there is enough sunlight in the UK to achieve this between April and September, which means we have to rely on food sources – such as oily fish, red meat, egg yolks and mushrooms – or supplements. This is especially challenging for vegans, as many supplements contain sheep’s lanolin.
“Editing tomato genes for provitamin D3 levels above recommended dietary guidelines can lead to better health for many, especially since tomatoes are a widely available and easy-to-eat food,” said Guy Poppy, a professor of ecology at the university. in Southampton.
Sign up for the First Edition, our free daily newsletter – every weekday morning at 7am BST
Tomato plants were created by making small changes to an existing tomato gene using an editing technique called Crispr-Cas9. “It’s like a pair of molecular tweezers that you can use to accurately cut a very small fragment of a gene to improve a desired trait in plants much faster than the traditional reproduction process and without introducing foreign DNA from other species.” said Jie Lee of the John Ines Center in Norwich, which is leading the study.
In this case, their focus was an enzyme found in tomato plants that usually converts provitamin D3 to cholesterol. By modifying this enzyme, the researchers were able to block this pathway, which means that provitamin D3 accumulated in the fruits and leaves of tomatoes.
They calculated that the amount of provitamin D3 in one tomato fruit – if converted to vitamin D3 – would be equivalent to the levels present in two medium-sized eggs or 28 grams of tuna. To turn this into active vitamin D3, the fruit still needs to be exposed to UVB light or could potentially be grown outdoors, something the researchers plan to test in upcoming field trials. The study is published in Nature Plants.
“This is a good example of using gene editing technology to make a very specific change in the harvest,” said Professor Gideon Henderson, chief research adviser at the Department of Environment, Food and Rural Affairs.
Such “precisely edited” crops are the subject of a bill set out in the Queen’s speech, which will allow genetically modified plants to be treated differently from genetically modified organisms (GMOs) – whose cultivation is governed by strict European rules that the UK hopes to move away.
“This is an example of the type of product that can go through traditional GMO legislation, but will do so very slowly in the current regulatory environment, and it could take decades to navigate the system,” Henderson said.
Unlike GMOs, tomato plants do not contain genes from other organisms and could theoretically be created by selective reproduction – albeit much more slowly. Such crops will be allowed under the proposed bill on genetic technology (precision farming), which the environment minister predicts will be adopted this year, potentially allowing the first genetically modified foods to be available by 2023.
Professor Katie Martin of the John Innes Center, who leads the study, said it demonstrated the potential of gene editing to be used to improve the nutritional value of food, and that the same technique could generate similar changes in any elite tomato variety. “This means that companies can introduce this trait in their patent-protected varieties, or it can be introduced in [the tomato variety] Gardener’s Delight, where it is not [patent] protection, “she said.
“[The technique] it may probably work well in other nightshade crops such as peppers, chili peppers, potatoes and eggplants.
An added benefit for growers is that they can potentially sell leaves or unripe fruit to supplement growers for processing into vitamin D tablets, Martin said.
Add Comment