No more bananas?!

This popular fruit is threatened with extinction as large plantations in the tropics are being attacked by a deadly fungal disease. Leading banana producers are trying to create a new sort that would be resistant to the infection, but they have not yet found a suitable candidate. Scientists offered their help, using modern biotechnology to modify the genetic make-up of the banana in order to make it resistant to the deadly disease while preserving its original form and taste.

Fruit or vegetable?
Most Europeans and Americans view bananas as a fruit, a dessert, something that accompanies a meal, but this attitude is not shared by the rest of the world. Bananas, not much different than the ones we know, are considered to be the essential part of the menu by nearly half a billion people from less developed tropical countries. The local population does not consider bananas to be a fruit because they have to be cooked or fried before being served as a meal. In local cuisine, they are used like we use potatoes or corn.

Bananas are grown in more than 120 countries on almost 10 million hectares of surface, yielding 100 million tons of crops. In underdeveloped parts of the world, bananas are the fourth most important food item after rice, wheat and corn. They have a high nutritional value and provide an important source of potassium as well as vitamins A, B6 and C. Because they are easy to digest, they are often the first food suitable for feeding babies. Nearly 90 percent of all bananas are grown on small farms intended for home use and local markets.

Bananas – the perfect food
The inhabitants of East Africa (Uganda, Burundi and Rwanda) hold the world record in banana consumption, eating 250 kg of bananas per person every year. The local term for banana “matooke” is a synonym for food. Bananas are also used to produce a popular beer which is an important source of vitamin B for the local population. The advantage of bananas over other crops is that they do not need to be planted anew each year. They flourish in different environments and yield crops throughout the year which means they represent a constant source of food even when other produce is still ripening. As the urbanization of the third world is under way and people move from the countryside to towns and cities, bananas are becoming an important source of food in city gardens as well, especially because they are so easy to grow.

Around 1000 different sorts of bananas that can be classified into 50 large groups are known in the world. Some banana trees can grow to be 15 meters tall, producing fruits up to 15 centimeters long. Bananas known in Europe and North America are of the Cavendish variety and represent merely a tenth of the total amount of banana crops produced in the world. They are mostly grown on large plantations in the tropics before finding their way to the shelves of our supermarkets. An interesting fact is that Americans seem to eat more Cavendish bananas than any other fruit, consuming more than ten kilograms per person each year. Apples place second with a little over seven kilograms per person every year.

Growing and selling Cavendish bananas is a booming business that involves large amounts of money. The expression “banana republic” denotes large banana producing countries where powerful international companies, such as once was the United Fruit Company, striving for the preservation of their lucrative industry have taken drastic measures, like violently overthrowing a country’s authorities. One of the more noticeable interferences by “banana corporations” in politics was, for example, the removal of the Guatemalan president from power in 1954 and the lending of ships to aid the unsuccessful invasion of Cuba’s Bay of Pigs.

The “primordial banana” and its billions of clones
Dessert Cavendish bananas that we are familiar with are also interesting from a biological point of view. In terms of their genetic composition, the majority of the one hundred billion Cavendish bananas eaten each year are identical. Regardless of how they find their way to our supermarket aisles – from Honduras or Thailand, Jamaica or Columbia – they are all genetic copies of their common predecessor, “the primordial banana”, brought to the Caribbean botanical garden from Southeast Asia in the beginning of the 20th century. Fifty years ago, this plant became the object of systematic multiplication and planting over vast areas of plantations for large-scale production of bananas as they are known today.

The very lack of genetic diversity among bananas of the Cavendish variety planted on vast plantations around the world represents the greatest danger that one of the world’s favorite fruits faces. A disease that can destroy a single banana plant is equally capable of successfully attacking others as they possess no different traits. An infection affecting one plantation could spread and damage others as well. If this should happen, the popular fruit would soon go missing from the shelves of our supermarkets.

The apocalypse of the banana
It might sound unbelievable, but the danger of an apocalypse of bananas is a thing to be reckoned with. This is especially true due to the fact that a large-scale extermination of bananas already took place in the middle of the previous century. Before that, our predecessors munched on bananas of the Gros Michel variety that were supposedly even bigger and sweeter than those of the Cavendish variety. In the beginning of the 20th century, however, a fungal infection called the Panama disease started spreading among banana plants. First, it broke out in Surinam, then it spread across the Caribbean for twenty years and finally reached Honduras, the world’s leading banana producer at the time (today it places third, after Ecuador and Costa Rica). Hoping to escape the disease, banana growers moved their plantations to new, uninfected areas, cutting down large portions of the rainforest.

By 1960, the migration strategy did not work anymore, because it entailed insupportable expenses. That is when the leading producers decided to replace the widespread Gros Michel variety with then a quite unknown Cavendish variety which was resistant to the Panama disease. A different variety naturally required different logistics which cost a lot of money, but there was simply no other way to go.

In 1992, however, a new fungal infection was discovered in Asia, this time harmful even to the Cavendish variety. Since then, the new form of the Panama disease has already devastated banana plantations in Indonesia, Malaysia, Australia and Taiwan, and has begun to spread across Southeast Asia. It has not yet reached Africa and Latin America, but the predominant opinion seems to be that it will spread there sooner or later.

How to save bananas before extinction?
Over the last few years, much effort has been invested into experiments to try and save one of our favorite banana varieties before vanishing from the shelves of our supermarkets. Using their extensive knowledge of biology, the scientists of today can go about searching for a solution in two ways. Applying the traditional method, they can try to crossbreed different varieties of bananas in order to create a new sort of a banana plant, resistant to the Panama disease. On the other hand, modern technology and knowledge enable them to create a resistant plant by using biotechnology and modifying the bananas genetic make-up. The proponents of the biotechnological approach wish to obtain genetically modified bananas which would retain the form and taste of those we know today. The only difference would be that the plant on which the fruit matures would be made resistant to the devastating disease due to its changed genetic code.

The trouble with natural crossbreeding of bananas is that they produce an extremely small amount of seeds. For every 300 bananas examined, only one seed is found, then carefully planted with the others in a greenhouse. Merely a third of them sprout. The first fruits suitable for assessing the success of the crossbreeding process take two years to grow. In addition to tasting and looking good, the acquired banana has to be able to withstand long periods of transportation. In fact, adequate replacements for the ailing Cavendish variety have already been found, but turned out, for example, to mature to fast or have a peel that was to thin to endure the long journey from the plantations to our markets.

The group, striving to find their solution in crossbreeding, will of course create a completely different variety of bananas that probably will not taste or look the same as the ones we are used to which is also the banana producers’ major concern. People are used to bananas as we know them today and countless cooking recipes have been written with the current variety in mind. Will we be willing to accept a substitute, as sweet as it may be, that will be of different form, size and taste?

Malaria

The World Health Organization estimates that several hundred million people are infected with malaria each year, of which more than a million die. Science has been waging war against this disease for more than one hundred years. A few decades ago it had seemed that victory lied ahead, but malaria adapted and struck again.

The deadly “mosquito conspiracy”
Malaria can kill a man in a matter of days. The disease is caused by a small, single-celled parasite, Plasmodium, which inhabits the red corpuscles of the infected person and starts to divide, doing so until the cells bursts. Destroyed blood cells can clog blood vessels causing damage to organs which may lead to the death of the affected person. It is most likely that, throughout the history of mankind, this tiny parasite has killed more people than any other disease.

For a long time people believed that malaria was caused by infected air. Hence its name: male aria, in Italian, means “bad air”. The key discovery in understanding the functioning of the disease was made in 1897 when a British military doctor, Ronald Ross, who was stationed in India, was testing the hypothesis that the true carriers of malaria were actually mosquitoes. Malaria experts of the time thought that the mosquito theory was quite absurd, but Ross decided to try it out anyway. He carried out an experiment that soon proved to be one of the most important ones in the history of medicine. He bred some mosquitoes and fed them blood taken from infected individuals. He wanted to find out if a malarial parasite can even survive inside a mosquito host. He tested his theory on several species of mosquitoes, but the parasite always perished. That was until he discovered a mosquito of the Anopheles genus and was surprised to find out that the parasite seems to thrive inside the intestines of this particular species of mosquitoes. Not only does the parasite survive inside the mosquito, it reproduces and waits to be transmitted to its next human victim.

Ross’s findings, for which he was also awarded the Nobel Prize in 1902, gave the human race a real chance to fight malaria for the first time ever. The idea was simple: as malaria was transmitted by mosquitoes, it was necessary to change the natural environment in a way that would make it as inhospitable for mosquitoes as possible. Extensive projects were started, draining swamps, stagnant waters and slow rivers where the populations of mosquitoes were most abundant. For the first time in history, the number of malaria infections started to dwindle. However, the method of draining was not as effective in certain tropical areas of the world, so the search for a more powerful weapon began.

Chemical weapons enter the battle
When fighting in the tropics, armies were horrified to find out that in these areas more soldiers were killed by malaria than by bullets, so they became very keen on finding an effective method of confronting the disease. During the Second World War, the Americans developed an insecticide that effectively destroyed the mosquitoes’ nervous system even when applied in small doses. After being dispersed over an area, it remained effective for several years. In addition to that, it was cheap. The insecticide was called dichloro-diphenyl-trichloroethane or DDT. After the war, the World Health Organization decided to use DDT to completely eradicate Malaria in the decades to come.

At first, the plan worked like a charm. In India alone, the number of malaria infections decreased from eight million cases before the eradication began to a “mere” fifty thousand. It seemed that the battle with malaria was already won when mosquitoes struck again. Their weapon against DDT was evolution. Every day, millions of mosquitoes come to life all over the world, and occasionally, some appear that have different traits than the majority. It only took one mosquito that had mutated in such a way that it became resistant to DDT. The insecticide had no effect on this particular mosquito, so it was able to reproduce without any difficulty and soon a population of DDT-resistant “supermosquitoes” started taking over the world.

Chemists put their heads together and started developing new insecticides, but mosquitoes eventually became resistant to those as well. The war on mosquitoes was a war on evolution itself. New insecticides had to be developed faster than mosquitoes could develop new defense systems with the aid of random mutations which kept the species from becoming extinct. As a rule, however, every new insecticide is more expensive than the previous one. In 1969, the World Health Organization gave up its struggle against mosquitoes and called off its plan to eradicate the chief carrier of malaria. Once more, the mosquitoes multiplied and the number of deaths caused by malaria increased again. The number of infections in India leaped from a couple of thousands to a couple of millions.

Because of mutations, the malarial parasite also became resistant to once relatively effective medicines, such as quinine, brought from Peru by the Jesuits in 1640. Some twenty years ago it seemed that humanity had lost its battle with one of the deadliest diseases plaguing the planet.

An ancient Chinese remedy turns out to be highly effective
In the 1970s, nobody in the West knew that the Chinese had developed a very effective remedy against malaria which was, in the spirit of the Cold War, kept top secret. The cure was discovered while – allegedly following Mao’s advice – carefully studying the functioning of more than 200 different mixtures intended for curing malaria, known in traditional Chinese medicine. And one of them truly worked.

Delving into traditional recipes, scientists stumbled upon 2000-year-old instructions for preparing the Quing Hau Su tea which was tested and proven to effectively cure malaria. They set about analyzing the tea’s ingredients and extracted the active substance that possessed the healing effects. Today, this substance is called artemisinin and is believed to be the most effective antimalarial drug known to man. Because of the Cold War and the concealment of the discovery from the world, it took thirty years before the medicine began to be used on a large scale.

The news about the miraculous antimalarial drug reached scientists from beyond the borders of China due to an article published in a Chinese medical review, a source that did not inspire much confidence at the time. In addition, the Chinese authorities did not allow for the ingredient to be analyzed by any laboratory outside of China. I took several years for westerners to find the plant that produced artemisinin and test the medicine themselves.

How to produce enough medicine for all the infected?
Because the drug turned out to be very effective, the demand for it today largely exceeds the capacity for its production. It takes eighteen months from planting Artemisia annua to isolating the drug which means that, using the conventional method, it is impossible to produce sufficient amounts of the substance to answer the needs of all those infected with malaria. That is why scientists today are striving to develop a method that would enable a faster and more efficient production of the drug.

By transferring some of the genes responsible for the production of artemisinin from the Artemisia annua plant into yeast plants, researchers have succeeded in making microorganisms produce artemisinic acid which, later on, undergoes a chemical procedure that produces the actual drug, artemisinin. With the help of yeast plants and this procedure it will most probably soon be possible to manufacture large quantities of the drug and save countless human lives. In Africa alone, two children lose their lives because of the devastating consequences of malaria every minute.

As with every new drug, however, precaution is necessary. In January 2006, the World Health Organization appealed to the pharmaceutical industry to stop advertising and selling drugs based solely on artemisinin. Last year, researchers realized that the mutation of a single amino acid could be enough for resistance to reappear. One of the best strategies in preventing malaria to become resistant to the latest, most effective solution is combining it with other antimalarials when treating patients. This reduces the possibilities for the potential survival of a mutated form of the disease and its spread over the world, preventing a disaster which has already occurred on several previous occasions.