Colorful Potatoes

Development of molecular markers as tools for breeding anthocyanin-containing potatoes.

Colorful potatoes are not only beautiful to look at, they are also beneficial to health because, unlike their pale counterparts, they contain larger quantities of colored secondary plant compounds known as anthocyanins. To make these available to as many people as possible, molecular tools for the targeted breeding of such potatoes were developed in the "MoMaPo" project (Molecular markers for the generation of potatoes with enhanced anthocyanin content).

© Fraunhofer IME | Birgit Orthen

Secondary plant compounds in human nutrition

Even in industrialized nations with excellent food supply and diversity, fruit and vegetable consumption is often relatively low and far below internationally recommended amounts. We cover most of our diet with a few staple foods such as rice, corn, wheat and potatoes. A predominantly plant-based human diet, especially if based on fruits and vegetables, can make a valuable contribution to human health, since plant foods always contain secondary plant compounds in addition to the classic macronutrients carbohydrates, proteins and fats.

Secondary plant compounds are organic compounds that are mostly found in specialized cells, where they play an important role for the entire plant: E.g. in protection against predators or through their attractive coloration. A large number of secondary plant compounds also have positive effects on human health, which scientists know how to exploit. For example, many pharmaceuticals are based on plant secondary metabolites. But even today, the mechanisms of action of some secondary plant metabolites are still obscure.
One large group of secondary plant metabolites are the water-soluble anthocyanins, which belong to the flavonoid group. They are found in the cell sap of almost all higher plants. They are mostly found in the flowers and fruits, where they are responsible for the sometimes intense red, violet or blue coloration. This is where their name comes from. It consists of two parts: Ánthos, the ancient Greek word for flower or blossom, and kyáneos, the ancient Greek word for dark blue or dark-colored. In plants, anthocyanins perform three main tasks: They absorb the short-wave UV light from the sun and re-emit the radiant energy as heat. This protects proteins and DNA molecules in the cells from the damaging effects of UV rays. In addition, the intense coloration attracts insects and other animals. They ensure the reproduction and spread of the plant. Furthermore, anthocyanins have a strong antioxidant effect. If the plant is exposed to oxidative stress, free radicals are formed, among other things, which react with oxygen molecules to form reactive oxygen radicals and have a negative effect on the plant's metabolism. Free radicals are also suspected of being associated with various diseases in humans. Anthocyanins are able to render free radicals harmless and therefore health-promoting effects are attributed to them. Studies in humans and animals have shown that anthocyanins have anti-inflammatory, anti-viral and anti-carcinogenic properties. In addition, positive effects on cardiovascular diseases, obesity, increased cholesterol levels and memory performance have been observed.

Most staple foods, such as wheat or rice, are relatively low in anthocyanins, so fruits and vegetables are currently the main sources of anthocyanins in the human diet. The potato is an exception to this rule, since, in addition to yellow- and white-fleshed potatoes, there are also old, lesser-known blue- and red-fleshed potato varieties whose color is due to the presence of anthocyanins. In South America in particular, many colored old landraces can still be found, which can be used for breeding modern high-performance potato varieties with high anthocyanin content.