Sigatoka Complex Causes Lethal Threat To World’s Banana Supply

A fast-advancing disease compound, known as the Sigatoka complex, could be a lethal threat to the world’s banana supply, according to plant pathologist Ioannis Stergiopoulos. The Sigatoka complex is made up of three fungal diseases — yellow Sigatoka, eumusae leaf spot and black Sigatoka. Of the three, black Sigatoka poses the greatest risk to the 100 million tonnes of bananas grown annually in almost 120 countries.

Stergiopoulos sequenced the genomes of eumusae leaf spot and black Sigatoka, and then compared results with the previously sequenced yellow Sigatoka genome.

He found that the three fungal diseases not only shut down the immune system of the banana tree, but the metabolism of the fungi also adapted to match that of the host plant.

“We have demonstrated that two of the three most serious banana fungal diseases have become more virulent by increasing their ability to manipulate the banana’s metabolic path ways and make use of its nutrients,” he told Digg.

Stergiopoulos pointed out Cavendish bananas — those most commonly found in the supermarket — are grown from shoot cuttings, which mean a disease capable of wiping out one plant could destroy them all.

“The Cavendish banana plants all originated from one plant and so as clones, they all have the same genotype — and that is a recipe for disaster,” he said.

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In order to prevent the global banana industry from being wiped out in the next decade, farmers need to make 50 fungicide applications to their banana crops annually. “Thirty to 35 percent of banana production cost is in fungicide applications. Because many farmers can’t afford the fungicide, they grow bananas of lesser quality, which bring them less income,” he said.

Source-Medindia