We’re bananas about our latest Pint of Science post! Sarah Schmidt is previewing her research on Fusarium wilt of bananas and how engineering resistance in bananas is a crucial part of our future food security.
Mendeley is proud to be partnering with Pint of Science for the third year running.
As an introduction to the great talks on offer we’re going to be previewing some of the most interesting here on the Mendeley Blog, featuring speakers from across all Pint of Science themes. You can follow along on our blog under the tag PintofScience17 or on Twitter under the hashtag #pint17.
The banana killer – How to engineer resistance to a devastating fungal disease of bananas
Every morning, I slice a banana in my breakfast cereals. And I am not alone. On average, every person in the UK eats 100 bananas per year. In other countries, it’s even more. In Uganda, people consume between 3 and 11 bananas per day!
Bananas are the most popular fruit in the world and the fourth most important food staple after wheat, rice and maize. The most traded banana cultivar is called Cavendish. This is the banana you find in supermarkets around the world – medium size with nice curves and a fresh yellow skin. Almost 50% of the bananas grown worldwide are Cavendish. Curiously, the Cavendish variety originates from England. A keen gardener at the Chatsworth estate grew the exotic plant in the greenhouse and named it after his employer Lord Cavendish.
The Cavendish banana became popular in the 1960s, when a devastating epidemic of Fusarium Wilt wiped out banana plantations in Middle America. This Fusarium Wilt epidemic almost led to a complete collapse of the banana export industry. Only the Cavendish banana was resistant and could be grown on the infested plantations.
Take a close look at your bananas!
Unfortunately, a new Fusarium wilt race appeared in the 1990s in South East Asia and this new race is able to infect Cavendish bananas and many other cultivars. Breeding bananas is incredibly time and space-consuming, because edible bananas don’t have seeds. They are so-called virgin fruits that can only be propagated clonally. If you have a close look at your Cavendish banana at home, you will notice the little black dots within the tasty fruit pulp. These little dots are the remnants of the stone-like seeds of wild bananas. Without seeds, breeding new varieties is painfully slow and certainly not fast enough to save the Cavendish.
That’s why I am exploring new ways of combating Fusarium wilt disease by taking leads from the causal agent: the soil-borne fungus called Fusarium oxysporum f. sp. cubense. The fungus infects the plants through the banana roots and grows within the plant’s water transporting system. Banana plants sense this attack and respond by the formation of gummy-like substances that block the transport system and eventually lead to wilting and collapse of the whole plant. This is an overreaction of the immune system that is similar to the fever attacks of a Malaria patient.
Like the Malaria pathogen, the Fusarium fungus secretes small proteins to manipulate the immune system of the host. These proteins are similar to secreted proteins of other Fusarium species that infect, for example, tomato plants. In tomato, some of these secreted proteins are recognized by immune receptors, which results in disease resistance. Using biotechnology, we can transfer the tomato immune receptors into banana to make them resistant against Fusarium wilt in banana. I am also employing the genes coding for small secreted proteins to develop diagnostic tools to identify the fungus in non-symptomatic banana plants. These diagnostics are important to halt the worldwide spread of Fusarium wilt and to prevent its entry to the export plantations in Middle America.
If we don’t prevent it, it will be the end of bananas in the UK.