Banana DNA mapped to create stronger crop | Science| In-depth reporting on science and technology | DW | 27.07.2012
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Science

Banana DNA mapped to create stronger crop

Two French research bodies have sequenced a banana genome as part of efforts to create a new, pest resilient variety. The banana DNA could help in food security issues.

France's CIRAD - a center for agricultural research for development - and the National Research Agency (ANR) say they have sequenced the DNA of banana. Led by CIRAD's Angélique D'Hont, the researchers were able to map the genome of a wild Asian strain called Musa acuminate - a component in every edible variety of bananas. They say their work is an important step toward understanding the genetics of the crop - and toward improving varieties and strengthening them against fungus and pests. But Angélique D'Hont says CIRAD is focused on cross-breeding rather than genetically modifying bananas.

DW: Angélique D'Hont, in terms of food security issues, how important do you consider your findings?

Angélique D'Hont: Eighty-five percent of banana production is consumed locally in tropical and sub-tropical countries. So, it provides a staple food and a major source of income for over 500 million people. And half of all production comes from only one cultivar [a variety of plant maintained through cultivation - the author] - or one group of cultivar derived from only one seed. And pests and diseases have gradually adapted to this cultivar.

So, we're talking about monocultures - pest have become resistant within these monocultures?

Yes.

So, how can your findings help farmers and cultivators beat the pest?

Because of this situation it is important to breed new varieties - new cultivar. But breeding bananas is quite complicated. Partly because bananas have to produce sterile fruit - that is, fruit without seeds to make them edible. And to make new bananas you have to perform cross-breeding, so you need a fertile plant. So, we have sequenced one banana genome type and we have identified 36,000 genes and we know the exact position of these genes on the chromosome. The next challenge is to find among these genes, which ones are important for conferring resistance to the main diseases and also for conferring good fruit quality.

Bunch of Bananas

Bananas are a staple food and major source of income around the world

And which are the main diseases?

There are two main diseases at the moment: the Panama Disease and the Black Sigatoka Disease.

And where do these diseases affect crops most - in which countries?

The Black Sigatoka is now all over the world and the Panama Disease - a new type - is in Asia only, but it will probably extend to other areas.

Now, you'll want to genetically modify…

No, in fact, the first step is to identify the gene that's important for resistance, and this information can indeed be used to modify by transgenesis - to modify current cultivar. But another approach, which is the one we're pursuing at CIRAD, is to breed new cultivar by crossing different cultivar with different types of resistance. By breeding. And knowing which gene and which genotype has the important gene will help the breeder to create new cultivar by classical breeding.

So, you're avoiding genetic modification, then.

There are two strategies - classical breeding and genetic transformation. At CIRAD at the moment we have chosen to work with the breeding strategy. But other groups are working with the other strategy. And the availability of the sequence will help both strategies.

What sort of a response do you expect to find from cultivators and also indeed from national governments - do you expect them to take this up? Because as we've been discussing bananas are a staple food, so do you expect them to readily accept what you come up with?

If there's a good quality banana that is resistant, I think they could adapt [to it]. Because the cost of using pesticides is important - it represents an important cost for agriculture. But I think the main difficulty will be for export bananas because the process for transporting and conserving bananas is calibrated for only one cultivar. Part of the banana production - about 15 percent which are exported to industrialized countries - they are transported in boats in refrigerated conditions and it's all been adapted to one cultivar, which is the Cavendish. And so the industry will have to adapt their processes, and it will represent a cost, and they may not be able to do it directly if the adaptation is too big.

So, essentially, this all comes down to money, doesn't it?

Yes!

Angélique D'Hont is a senior researcher with CIRAD - Agricultural Research for Development - and is based in Montpellier, France.

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