Unpeeling bananas’ genes may help produce disease-resistant varieties

Washington - Scientists have for the first time sequenced the banana genome, which may help save the humble yellow fruit from imminent collapse.

Bananas are a staple food around the world. But the fruit faces pests and diseases that threaten to wipe it out across the globe.

The achievement opens the way for developing better banana crops that are naturally resilient against parasites and other stresses.

“The banana is very important, especially for tropical and subtropical countries,” the Discovery News quoted Angelique D’Hont, a geneticist at CIRAD, an agricultural research center in  Montpelier, France, as saying.

“Because the future of the banana is in danger, the sequence will help to produce resistant bananas and avoid the utilization of pesticides. It will be much easier now to identify genes which  are important,” D’Hont stated.

To decipher the banana’s genetic strengths and weaknesses, D’Hont and a large group of colleagues spent two years sequencing a variety of banana called Musa acuminate, which is a  simpler relative of the Cavendish.

Once they put together the sequence, the researchers discovered several genes that may be involved in pest resistance.

Among other findings, the researchers identified genes involved in ripening after the application of ethylene, which is often added to green bananas during transport. The sequence also

revealed that the banana duplicated its entire genome three times (making an extra copy of every single gene in its genome) -- including once 100 million years ago and once 60 million years

ago

Putting together the sequence took so long because, compared to many other crops, the banana genome is extremely complex. Even though all bananas are clones of each other, the

original gene forms that came from mother and father plants remain different from each other -- unlike in seeded crops that tend to become inbred, said Simon Chan, a plant biologist at the

University of California, Davis.

What’s more, bananas have three copies of each chromosome, just like other seedless plants. And for many genes, all three copies are different.

The variety of banana used in the new study had just two of each chromosome, making it simpler than the Cavendish. But by finally deciphering its sequence, scientists will be able to move

on to our beloved breakfast fruit and compare the differences.

Knowing the genetic sequence of bananas is a major step toward isolating key genes that will eventually lead to a better banana, Chan said. Future varieties may be able to resist both

droughts and diseases, while still tasting good and travelling well.

Those developments are especially important in the developing world, where starchy varieties of bananas supply substantial amounts of calories to the human diet, especially in Uganda and

other East African countries. There, Chan said, losing the banana crop would be a humanitarian disaster.