Sometimes things food-related pop into my head unbidden. Today, the word pomato made an appearance. Pomato? Where had I heard that? I looked it up and then remembered that I had started some research into this subject a few years ago. Most likely, I was distracted by some shiny object or another before writing anything down. And, the pomato plant itself is just such a shiny object. You see, there is no such thing as a pomato fruit (or vegetable). That is, there is no such thing as a fruit that is a weird cross between a potato and a tomato. There are plants that you could call pomato plants, but the fruits they bear are just plain old tomatoes. What would such a real tomato fruit look like anyway, and why am I raining on your parade?
Is the Pomato Plant Real?
Well, the reason I’m being a stick in the mud about the pomato, sometimes called the tomtato, is that the plants you might see pictured on the internet are simple grafts between a tomato plant and a potato plant. They cannot be propagated as a distinct plant in any way. If you planted the potatoes from such a plant, you’d get a potato plant. If you planted seeds from the tomatoes, you’d get a tomato plant. There is no genetic engineering feat going on. A grade-school student can pull this off with the right instruction.
Potatoes and tomatoes are closely related. They are both part of the nightshade family. They are so closely related that you can take a scion, or graft from a tomato plant and graft it onto a potato plant and the two will fuse together, cooperate fully, and grow. The parent plant forms the rootstock, consisting of the potato plant and its roots or potato tubers. These will do what roots do. And the tomato part of the plant, grafted onto the rootstock, will produce tomatoes.
The plant itself does have some advantages of both species. For example, potatoes are more resistant to cold than tomatoes, so a so-called pomato plant can withstand frost. Tomato plants are more resistant to heat, so the pomato plant is more heat-resistant.
While there may be some distinct advantages to grafted pomato plants, a big problem is that potatoes and tomatoes can transfer diseases between one another. Potatoes are prone to certain diseases, as are tomatoes. Splicing them together means that the root end of the plant can transfer potato diseases to the tomatoes, and the tomatoes can transfer diseases to the potatoes. Common tomato and potato diseases like blight, mosaic virus, and various fungal and bacterial infections can be spread from plant part to plant part. So, what you have is a plant with more disease problems. Potatoes and tomatoes are normally planted far apart for this very reason.
So, you cannot try a “pomato fruit.” You can try a tomato from a tomato plant grafted onto a potato plant. Unfortunately, it’s just a tomato.
The Real Pomato Hybridization Attempts
There have been attempts to create a real pomato! By real, I mean a plant that is created through genetic engineering. Ideally, such a plant would have novel characteristics all its own. It would produce fruits that were different than regular tomatoes.
Parade-raining time again. Such efforts were never truly successful. The first experiment to produce a pomato plant was performed by Georg Melchers of the Max Planck Institute for Biology in Tübingen in 1977. Using protoplast fusion techniques, he managed to produce a plant.
The idea was to produce a plant that had potatoes beneath the ground and tomatoes above the ground. Unlike the aforementioned grafted frauds, however, these plants would reproduce normally while providing both edible potatoes and tomatoes. That would be useful, don’t you think? Unfortunately, produced neither real potatoes nor real tomatoes. Yes, tomatoes and potatoes are closely related, but you can’t get them to marry up and have children that easily.
In 1994, a more or less real pomato was produced at the Max Planck Institute for Plant Breeding. Research Lewen-Dörr and a company called Green Tec produced hybridized plants that were, as they described, “vigorous.” Otherwise, they were mostly like potato plants except for one difference: they produced yellow flowers. Potato flowers are normally white or off-white.
The type of somatic hybridization these experiments tried can and does work. It is successfully used for citrus fruits, for example. But citrus fruits are much more closely related than potatoes and tomatoes. 1,2
Let’s Throw in Some Eggplants!
An article in The Times of India describes a “brimato” plant that was created using a pomato plant. It is described as an engineering breakthrough. In reality, a potato and tomato grafting was created, and then an eggplant (brinjal in India) was grafted onto the result. It is not a hybrid as the article claims. The difference is easy to spot. A true hybrid would produce one type of new fruit that shared characteristics of its parents. A grafting simply produces two or more different kinds of genetically distinct fruits.
Grafting Is a Common Practice
Grafting plants or trees is a common practice. For instance, all the members of the Prunus genus (plums, nectarines, apricots, cherry, almond, pluots, peaches, etc.) can generally be grafted together. Believe it or not, more than one type of fruit tree can be grafted onto the same rootstock to produce a tree that grows more than one type of fruit!
But, the fruits do not share characteristics with one another. If you graft a plum tree and an apricot tree onto a single peach tree seedling, the result is not a “Plumeachacrot.” It’s just a tree that has the rootstock of a peach and different branches that produce either plums or apricots.
While there is nothing wrong with producing a grafted “pomato” plant, don’t let anyone try to sell you one of them and tell you it’s a real pomato plant. No matter how much one part of the plant depends on the other, they are still two distinct genetic entities, and planting either will reproduce only itself. Advertisements that proclaim you can purchase a “single plant that can grow tomatoes and potatoes” are fraudulent if they imply that the plant can be used to produce tomatoes and potatoes more than once. On the other hand, a grafted plant can be quite useful
The name pomato implies, to my mind and based on the original intention of the term, a hybrid between a tomato and a potato. At the risk of repeating myself, there is no such thing. However, if you buy a grafted plant from a reputable nursery, they can be useful for those who have limited space for growing vegetables, such as in urban areas, in rooftop container gardens, and the like. A grafted potato and tomato plant will allow you to get a dual harvest from one plant. But, to repeat this harvest, will have to buy a new plant.
- Renneberg, Reinhard. Biotechnology for Beginners. Netherlands, Academic Press, 2023.
- Principles and Techniques in Vegetable Grafting. United States, CRC Press, 2024.