Many of us have been guilty of binning a mushy, overripe banana – but now scientists say they have a solution with the launch of a genetically engineered non-browning banana.
The product is the latest in a series of gene-edited fruits and vegetables designed to have a longer shelf life. Scientists say the technology is emerging as a powerful new weapon against food waste, which occurs globally on an epic scale.
The banana, developed by Tropic, a biotech company based in Norwich, is said to remain fresh and yellow for 12 hours after being peeled and is less susceptible to turning brown when bumped during harvesting and transportation.
“Food waste is a big contributor to greenhouse gas emissions. It’s very bad, clearly,” said Gilad Gershon, the chief executivet of Tropic. “Bananas are the fourth biggest crop globally, but also one where the perishability is very high. Some estimates say that 50% of the bananas grown are never eaten.”
The company has also developed a slow-ripening banana that has been approved in several countries, which it plans to launch later in the year. Other research teams are working on lettuce that wilts more slowly, bruise-resistant apples and potatoes and identifying the genes that determine how quickly grapes and blueberries shrivel.
An estimated 33% of the produce that is harvested worldwide is never consumed due to the short shelf-life of many fruit and vegetable products. Bananas are among the most thrown-away foods, and a government survey suggests that Britons routinely bin 1.4m edible bananas every day. Since commercially grown bananas lack seeds they cannot be hybridised in the way most fruits can.
“Bananas are asexual,” said Gershon. “There’s no real breeding in bananas. We’re eating today the same bananas as our grandparents were eating in the 1950s. The only real opportunity we have to adjust the banana to meet the challenges the industry is facing is through gene editing.”
The company worked out how to disable a gene responsible for the production of an enzyme called polyphenol oxidase, which causes browning. The same gene is silenced in Arctic apples, a genetically modified variety, which has been sold in the US since 2017, and blocking the production of polyphenol oxidase has been shown to work in tomatoes, melon, kiwifruits and mushrooms. In the bananas, Tropic made precise changes to existing genes without introducing foreign genetic material.
The company already has the go-ahead to sell the non-browning bananas, which are yet to be given a name, in the Philippines, Colombia, Honduras, the US and Canada. Gershon says the product is expected to comply with the requirements of the UK’s Genetic Technology (Precision Breeding) Act, once secondary legislation is passed later this year, which could pave the way for the fruit to be sold in England.
Dr Martin Kottackal, of the Khalifa Center for Genetic Engineering and Biotechnology in Abu Dhabi, says gene editing can be used to target several aspects of the ripening process. His team is investigating non-browning and “stay green” genes and another pathway involved in the production of ethylene, a gas released by fruits that triggers the ripening process. “We’re working on tomato, lettuce, eggplant,” he said. “They’re all in the pipeline.”
Other teams are investigating genes that influence the waxy, protective layer, known as the cuticle, that covers the surface of a fruit. A thicker cuticle can protect against fungal infections in apples and tiny cracks in soft fruits, such as grapes and blueberries, which cause them to shrivel.
Prof Cathie Martin, of the John Innes Centre in Norwich, said there was increasing interest in developing products with a longer shelf life. “The reason russet has been a favourite potato with McDonald’s is because it doesn’t go brown,” she said. “Non-browning is definitely a desirable trait.”
Martin’s team developed a genetically modified purple tomato that is unusually rich in antioxidants and that is marketed in the US on the basis of its health benefits. Its antioxidant content also means it softens less quickly after becoming ripe. “The purple tomatoes have an amazing shelf life, at least twice and sometimes four times longer,” she said. “We haven’t promoted it that much, but I do think it’s a big selling point.”
Prof Jonathan Jones of the Sainsbury Laboratory has led the development of a blight-resistant maris piper potato that reduces the need for pesticide, but which is also protected against losses caused by blight in storage.
“In agriculture and food, it’s not one big problem, it’s a lot of little problems and reasonable-sized problems,” he said. “There are solutions to all of them in genetics. It allows you to approach, in a faster and more focused way, solutions to these problems.”
