BY RONY SWENNEN AND NORA CAPOZIO. How many apple varieties can you find at your local market? Probably at least four or five. We are used to eating yellow, green, red apples, and they can be juicy, sweet, tart, firm, crispy… What if instead I asked you: how many different kinds of bananas do you know? I bet that most of you will say one.

Ronny Swennen & Nora Capozio

And, in a way, you would probably be right because there is only one export banana variety. It is called Cavendish and it is used as a dessert and snack. This is the only variety that Western country customers eat. If you’re used to seeing rows and boxes of yellow Cavendish bananas at your local supermarket, it might come as a surprise that bananas can be found in many different colours, shapes and sizes and can be eaten raw, fried, grilled, boiled. You can even make beer with bananas!

There may be up to 1,000 different varieties of bananas in the world. We don’t know how many exactly there are, but we know for sure that there is one place where you can find the largest concentration of banana diversity in the world. As strange as it may sound, this place is right here, at KU Leuven!

Building on more than 100 years of banana research tradition in Belgium, KU Leuven hosts the world’s largest banana genebank, known as the Bioversity International Musa Germplasm Transit Centre (or ITC for short). Founded in 1985 and now managed by Bioversity International under an international agreement with Belgium, the collection contains samples of edible and wild species of banana coming from all over the world.

Diversity holds the key to food and nutrition security

To explain why conserving crop diversity is so important, let’s take a moment to consider another food source: the potato.

In the 1840s, a deadly disease called late blight appeared in Ireland. Caused by a fungus, the disease attacked potatoes, the main food staple in Ireland at the time, devastating harvests for years. The famine that resulted – known as the Irish Potato Famine or Great Famine – killed one million people and forced two million to emigrate. One of the reasons why late blight struck Ireland so hard was the low genetic diversity of the potatoes that were grown there.

Genetic diversity make all living organisms less vulnerable to stresses, whether they are due to pests or diseases or a changing climate. Diversity is a treasure that must be safeguarded, explored and used more widely so that we can make our crops more nutritious, productive and resilient.

Just as the potato is a symbol of the Irish diet, bananas are a staple crop in many countries, such as Uganda, Rwanda and Burundi, where people consume up to 11 bananas each per day.

This is exactly why we are maintaining all these banana varieties at the ITC: to secure the long-term conservation of the entire banana genepool for the benefit of current and future generations.

Bananas provide food, nutrition and income to hundreds of millions of people. Just as the potato is a symbol of the Irish diet, bananas are a staple crop in many countries, such as Uganda, Rwanda and Burundi, where people consume up to 11 bananas each per day. It is therefore no surprise that in Uganda, the local word for bananas – matooke – means food.

Bananas in small test tubes

Seed storage is the most common way to preserve crop genetic diversity. Since bananas normally do not produce seeds, here in the ITC genebank we conserve them as small plantlets in vitro (in test tubes) under slow growth conditions at 16 °C. Looking after this collection and ensuring that these little plants stay healthy is a labour-intensive and year-round challenge.

The ITC collection is also internationally renowned as the safest source of healthy banana planting material. We distribute only those samples that have been found free of pests and pathogens.

Bananas in the freezer

For security and long-term storage, we also freeze banana samples at -196 °C, the temperature of liquid nitrogen, using a process called cryopreservation. This extremely low temperature stops all biological and chemical processes, so that the plant remains unaltered for thousands of years and can be revived into a full banana plant as needed.

For security and long-term storage, we also freeze banana samples at -196 °C, the temperature of liquid nitrogen, using a process called cryopreservation.

More than 60% of the banana samples in Leuven are cryopreserved. For security reasons, we also store a backup in Montpellier, France.

From the lab to the farm

In addition to conservation purposes, we at Bioversity International and our KU Leuven colleagues use the genebank to carry out research that can benefit farming communities around the world.

For example, we are studying how banana varieties that are naturally-rich in vitamin A can become part of East African diets to fight vitamin A deficiency, which every year causes half a million children to go blind. Half of those die from infections. Many of these children live in Africa where bananas are the fourth most important food crop – swapping one variety for a vitamin A-rich variety could make all the difference. So we sent vitamin A-rich banana varieties from the ITC to Burundi and the Democratic Republic of the Congo, reaching around 5,000 people and we plan to expand into Kenya, Tanzania and Uganda.

We are also developing screening methods to select those banana varieties conserved at the ITC that are tolerant to drought. This is particularly important given the predicted rise in temperatures in the tropical and subtropical areas where bananas are cultivated.

In 30 years of activity, the ITC has distributed over 17,000 banana samples to researchers and farmers in 109 countries. On average, 75% of the samples go to users in the main banana growing regions – Africa (27%), the Americas (25%) and Asia and Pacific (23%) with the remainder sent to universities and research centres in Europe.

Conserving, understanding and using crop diversity plays a fundamental role to make agricultural systems all over the world more nutritious, resilient and sustainable. And our research on bananas here at KU Leuven is part of this effort.

On 23 January 2017 the ITC celebrates its 30th anniversary with an event at KU Leuven attended also by Belgium Deputy Prime Minister and Minister for Development Cooperation, Alexander De Croo.