Plant scientists based in Norfolk are celebrating after a genetically-modified purple tomato they have developed cleared a regulatory hurdle in the US.

Researchers at Norfolk Plant Sciences Ltd - a spinout from the world-leading research institutes the John Innes Centre and The Sainsbury Laboratory - welcomed a decision by the United States Department of Agriculture (USDA) which helps clear the way for its tomato seeds to be sold there.

It means American gardeners should be able to grow the company's nutritionally-enhanced high-anthocyanin purple tomato from spring 2023.

The company - founded by Professors Cathie Martin and Jonathan Jones - is one of the UK’s first GM crop companies and aims to commercialise their research into plants with enhanced health-giving compounds.

Professor Martin first developed the anthocyanin-rich purple tomato in 2008 by engineering a precise genetic “on switch,” derived from an edible flower.

“This is fantastic, I never thought I would see this day. We are now one step closer to my dream of sharing healthy purple tomatoes with the many people excited to eat them,” she said.

“The bittersweet thing is that the tomatoes will be on sale in America and not the UK as well. But the plus side is that by focusing on home growers we will be consumer oriented, and we will be able to get feedback and interest needed to develop other products.”

Hundreds of people in the US have already expressed interest via the Big Purple Tomato website in buying tomatoes and seed once they become available, said the firm.

Professor Jonathan Jones of The Sainsbury Laboratory said: “When Cathie and I founded NPS nearly 15 years ago to bring to market health-promoting, genetically enhanced purple tomatoes, invented in the UK, we never thought it would take so long to obtain regulatory approval. This is a red-letter day for crop improvement, with approval of a beneficial product by USDA, after careful scrutiny of a detailed information dossier that describes its properties.

“We also look forward to sensible regulatory frameworks for such products in the UK, and effective methods to protect our major crops from disease, using genetics instead of chemistry.”

Anthocyanins are antioxidants associated with various health benefits and are key to an anti-inflammatory diet. Studies suggest both antioxidants and anthocyanins can reduce incidence of cancer, improve cardiovascular function, and improve health and well-being.

Nathan Pumplin, chief executive of Norfolk Plant Sciences’ US-based commercial business, said: “This decision shows how the updates to APHIS’s regulatory framework will enable independent scientists and small companies to develop and compete on the market with better products, to the benefit of consumers and climate.

"This decision is a big milestone, which brings us much closer to a commercial launch of purple tomatoes. We are optimistic that we can begin limited distribution of purple tomatoes in the US in 2023.”

Purple-skinned tomato varieties already exist but these do not accumulate useful levels of the healthy compounds, the scientists explained.