Scientists Create Tomatoes Genetically Engineered To Boost Vitamin D

Tomatoes that have been genetically modified to generate vitamin D, sometimes known as the sunshine vitamin, might be a simple and long-term solution to a global health issue.

Researchers employed gene editing to switch off a particular component in the tomato plant's DNA, which resulted in an increase in provitamin D3 in both the fruit and leaves. After that, UVB radiation was used to convert it into vitamin D3.

Vitamin D is produced in our bodies when our skin is exposed to UVB sun, but diet is the most important source. Millions of people may benefit from this new biofortified grain, which has been linked to an increased risk of cancer, dementia, and many other main causes of death. Vitamin D deficiency has also been connected to a higher severity of Covid-19 infection, according to research.

Tomatoes have very low quantities of provitamin D3, also known as 7-dehydrocholesterol (7-DHC), in their leaves. Provitamin D3 is not generally found in ripe tomato fruits.

Professor Cathie Martin's team at the John Innes Centre used CRISPR-Cas9 gene editing to change the genetic coding of tomato plants such that provitamin D3 accumulates in the fruit. Provitamin D3 levels in the leaves of the modified plants ranged from 600 ug (micrograms) per gram of dry weight. Adults should have 10 ug of vitamin D every day.

When growing tomatoes, the leaves are normally discarded, but those from the altered plants may be utilized to make vegan-friendly vitamin D3 supplements or to fortify meals.

“We’ve shown that you can biofortify tomatoes with provitamin D3 using gene editing, which means tomatoes could be developed as a plant-based, sustainable source of vitamin D3,” said Professor Cathie Martin, the study's corresponding author.

“Forty percent of Europeans have vitamin D insufficiency and so do one billion people worldwide. We are not only addressing a huge health problem, but are helping producers, because tomato leaves which currently go to waste, could be used to make supplements from the gene-edited lines.” 

Previous study looked at the molecular mechanism of how 7-DHC is utilized in the fruit to make compounds and discovered that it is converted into other molecules by an enzyme called Sl7-DR2.

The researchers took advantage of this by using CRISPR-Cas 9 to turn off the Sl7-DR2 enzyme in tomato, allowing 7DHC to accumulate in the fruit.

They tested the amount of 7-DHC in the leaves and fruits of these modified tomato plants and discovered that both the leaves and fruits of the edited plants had much higher amounts of 7-DHC.

Tomatoes collect 7-DHC in both the flesh and the skin.

The researchers next used UVB light on leaves and sliced fruit for 1 hour to see if the 7-DHC in the altered plants could be converted to vitamin D3. They discovered that it did, and that it was quite successful.

One tomato provided the same amount of vitamin D as two medium sized eggs or 28g tuna after being exposed to UVB radiation to convert the 7-DHC to Vitamin D3.

According to the study, sustained UVB exposure, such as during sun-drying, can boost vitamin D levels in ripe fruit.

The tomato plants' growth, development, and yield were unaffected by blocking the enzyme. Because other closely related plants, such as aubergine, potato, and pepper, have the same metabolic route, the procedure might be used on them as well.

The UK government established an official inquiry earlier this month to determine whether food and drink should be fortified with vitamin D to address health disparities.

Plants are relatively poor providers of vitamin D, and most diets contain little of it. When the skin is exposed to sunshine, the body produces vitamin D3, which is the most accessible form of vitamin D. Because the sun isn't strong enough for the body to manufacture vitamin D naturally in the winter and at higher latitudes, individuals must acquire it through their food or pills.

“The Covid-19 pandemic has helped to highlight the issue of vitamin D insufficiency and its impact on our immune function and general health. The provitamin D enriched tomatoes we have produced offer a much-needed plant-based source of the sunshine vitamin. That is great news for people adopting a plant-rich, vegetarian or vegan diet, and for the growing number of people worldwide suffering from the problem of vitamin D insufficiency,” said Dr. Jie Li, the study's first author.