You stroll through the shopping aisles of your local supermarket to get your weekly supply of groceries. As you reach out to a bunch of tomatoes you are struck by an unusual sight. These tomatoes are not red, but deep purple!
After recent events, this scenario might not be too far away. Already in 2008, Prof. Cathie Martin, plant scientist at the John Innes centre in the UK, successfully grew tomatoes with a deep purple colour [1]. This was achieved by incorporating two transcription factors of the snapdragon into the tomato’s genome [2]. The mentioned transcription factors are parts of the DNA, which influences in which way other genes are being read. As a result, these tomatoes produced significantly higher amounts of anthocyanin, a pigment native to blueberries, eggplants and, to some amount, our ordinary tomatoes. This pigment creates the striking purple colour. But it has a lot more benefits than just looking pretty! Anthocyanin is also a valuable antioxidant that has anti inflammatory functions and it also reduces one’s cancer risk!
So these colourful tomatoes have been around since 2008, but why should you know about them right now? That is because on the 7th September of 2022, the United States Department of Agriculture has published a statement, saying that these tomatoes are “unlikely to pose an increased plant pest risk compared to other cultivated tomatoes”, which no longer makes them a subject to regulation. This is a huge step towards the genetic engineering of crops! Soon these purple tomatoes might be allowed for cultivation and even for private growing. To get their product out into the public, Cathie Martens founded a company called Norfolk Plant Sciences, together with Prof. Jonathan Jones, and in 2023, they want to sell the first purple cherry tomatoes in selected pilot markets. At some point, US citizens might even be able to buy seeds, to grow their own antioxidant-stuffed tomatoes in their private backyard!
Another interesting aspect is that these crops have been designed to appeal to the final consumers and not to famers or companies. First of all, these fruits are obviously purple, so the fact that they are genetically modified is not only super transparent for the consumers, but it is even part of their unique selling point. The effect of this genetic engineering is fully directed towards the shopper in the end, it is not some sort of resistance that the crop gained and it also is not any form of enhanced growth, but it is just a healthier, colourful tomato. In a nutshell, when going to the shop, you will instantly be able to tell that these crops have been genetically modified and you will also see that these changes were made to create a healthier tomato for you as a customer! As a cherry on top, it was discovered that the purple cousins of our ordinary red tomatoes have an improved shelf life, so at home, they stay fresh twice as long as classic tomatoes!
These tomatoes sound amazing, how come they were not made years ago? Well, they were actually made many decades ago, only then they were made to be bigger and give a higher yield, rather than to be purple.
For thousands of years, crops have been cultivated and modified to meet human demands and desires [3]. This has been done through selective- and cross- breeding, to give bigger yields, longer shelf life, or even faster growing. For example, the widely grown crop known as corn or maize, was before human intervention very different from today [4]. Corn was originally domesticated from a species of grass called teosinte, which had drastically less food on them.
More recently, a new way to modify crops (and other organisms) has been developed: Genetically engineered organisms (GMO). Utilizing synthetic biology, the whole process of modifying crops has been greatly sped up, while also giving more control over the changes, and allowing for more exciting changes. However, as mentioned before, how come GMOs have to be approved before they may be used commercially, while traditionally engineered crops do not?
Well, as many of you may know, there is an ongoing debate whether GMOs are good or bad for humans and the environment. There are valid arguments for both sides. Let’s take an example. Say you were to genetically modify a large scale crop, so that they would naturally produce their own pesticide. Farmers would no longer need to supply the crops with pesticide, which would save them time and money. However, the pesticide produced by the crop might not only affect the targeted pests eating the crops, but also non-targeted organisms such as butterflies, or bees; pollinators. The genetically engineered crop would save time, money, and resources, but would reduce the population of pollinating organisms.
This example might sound very familiar, and that is because it is based upon BT corn: a crop engineered to produce its own pesticide [4]. It was speculated that this pesticide might affect the monarch butterfly; a non-target pollinator. Public outcry over this speculation led to independent scientists to look into the problem. Their findings were that the monarch butterfly would not be significantly more affected by the pesticide, than they would be from conventional chemical pesticides.
This brings up an important topic within synthetic biology: Biosafety and biosecurity. The two terms are very closely linked, with a key minor difference. In essence, biosafety is the handling of biological material to protect humans and the environment in the event of a leakage. Biosecurity is the process of minimizing the risk of theft, misuse, loss, or unauthorized release of GMOs into nature. In a nutshell, biosafety is protecting humans and the environment from organisms, and biosecurity is protecting the organism from ill-meaning people.
When modifying organisms, especially if planning to release them, it is very important to research and find any potential unforeseen effects of the organism in nature. One should also find ways to implement safety features in the organism/technique, minimizing the risk of misuse. In the case of the BT corn, the GMO ultimately posed no adverse effect to non-targets. However, had biosecurity been done more thoroughly, and released together with the plant, then the public outcry could have been avoided, reducing public mistrust towards GMOs.
Taking into account biosecurity when developing GMO crops can, among other things, greatly increase the public’s opinion and eagerness to try GMOs, such as the purple tomato. I know I will be picking them up if I see them!
Sources
[1]: https://www.wired.com/story/a-gmo-purple-tomato-is-coming-to-grocery-aisles-will-the-us-bite/
[2]: https://edition.cnn.com/2022/09/17/business-food/purple-tomato-gmo-scn-trnd/index.html
[4]: https://en.wikipedia.org/wiki/Zea_(plant)#Origin_of_maize_and_interaction_with_teosintes
