With vegan and vegetarian diets on the rise, deficiencies in vitamin D are becoming increasingly common. Jie Li, postdoctoral researcher at the John Innes Centre at Norwich Research Park, explains how she is using gene editing to fortify tomatoes and play ‘ketchup’ on this global public health issue.

Each month, those working at the pioneering heart of Norwich Research Park tell us how their work is shaping the world we live in. Read their stories here.

What does your research entail?

My research uses biotechnologies, such as gene editing, to enrich food sources with essential vitamins and phytonutrients. Gene editing is like a pair of molecular tweezers. You could use the technique to snip out a small fragment of a gene and alter the pathway to enhance nutrition in plants. My research is focused on biofortifying tomatoes with vitamin D3.

Biofortification is an efficient way to address vitamin deficiencies, not only with tomatoes. We believe there is potential to explore similar possibilities in closely related plants such as pepper, aubergine and potato.

I am also a board member of the EDESIA PhD programme, funded by the Wellcome Trust, to advance major aspects of plant-based nutrition and health – from crop to clinic.

Why is vitamin D important?

Vitamin D is known as the sunshine vitamin. It is created in our body after the skin is exposed to ultraviolet B (UVB) light, but a major source of vitamin D is our diet, fish in particular. Most plants contain very little vitamin D and, with the growing popularity of plant-based diets, there is a clear and urgent need for sustainable, plant-based sources of vitamin D.

Approximately one billion people worldwide are affected by insufficiencies in vitamin D, which is associated with a negative impact on immune function and inflammation. It’s also linked to a higher risk of cancer, dementia and depression. Studies have even linked vitamin D insufficiency with increased severity of Covid-19 infection.

In the UK, the average intake of vitamin D from dietary sources is about three micrograms per day but the recommended daily intake is 10 micrograms. Two medium-sized biofortified tomatoes could potentially fill this nutritional gap. Engineering vitamin D in plants is a novel and economic way to address the insufficiency, with the added potential for making vegan-friendly supplements from leaf extracts of the vitamin D enriched plants.

Why does your research focus on tomatoes?

Tomatoes naturally contain the building block of vitamin D3 – called provitamin D3 or 7-dehydrocholesterol (7-DHC). But provitamin D3 does not normally accumulate in ripe tomato fruits. Gene editing enables us to introduce or enhance some traits much more effectively, precisely and much more rapidly than traditional breeding processes.

I engineered provitamin D3 in tomatoes by using gene editing to block an enzyme called 7-dehydrocholesterol reductase 2 (Sl7-DR2). Blocking this enzyme in tomatoes had no effect on growth, development or yield; the accumulated provitamin D3 can then be converted to vitamin D3 through UVB irradiation. After treatment with UVB, one tomato contains the equivalent levels of vitamin D3 as two medium-sized eggs or 28 grams of tuna.

Why did you decide to pursue a career in science?

I got my bachelor’s degree in Agronomy from China Agricultural University in Beijing and took a gap year working in the lab. I was very lucky to get an opportunity to join the summer school at the John Innes Centre where I spent eight weeks in 2012, which inspired me to do my PhD.

It was a gradual process to decide to become a scientist, but with the support of my supervisor Prof Cathie Martin and the wonderful science environment at Norwich Research Park, I came back to Norwich in 2013 and have been here ever since!

What’s the best thing about working at Norwich Research Park?

Norwich Research Park is a diverse, respectful and collaborative working environment. It is exactly the kind of environment that can generate great science and give young scientists the right support or mentorship to develop their careers.

The John Innes Centre and Quadram Institute Bioscience just completed an application for funding from the Biotechnology and Biological Sciences Research Council (BBSRC) to establish a Biofortification Hub that will aim to develop new biofortified foods and test their nutritional efficacy. We're trying to help address global health problems, which requires that we work with growers, food companies, nutritionists and policymakers.

This work cannot be achieved by any single scientist, which is why the collaborative environment of Norwich Research Park is the perfect place to achieve this. If we're successful, we will bridge the gap between academic research, food production and regulatory bodies to raise awareness of the importance of balanced nutrition for a healthy lifestyle.

What do you get up to when you are not working?

Norwich is a beautiful place. Scientific work requires very high levels of concentration, so I love going for walks in the city to relax and stay healthy. I’m also a big fan of Lego. I enjoy the process of creating with those small bricks, including Hogwarts Castle from Harry Potter!

Jie Li is a postdoctoral researcher at the John Innes Centre at Norwich Research Park.