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Banana genome to be unravelled

作者:訾涅瀑    发布时间:2019-03-06 04:19:00    

By Andy Coghlan The banana is to be the first edible fruit to have its genetic code unravelled, a global consortium has announced. The first plant genome to be sequenced was the mustard cress Arabidopsis thaliana. Rice was next, but the companies that sequenced it have been criticised for not making the data freely available. Now bananas – genus Musa – are go. A global consortium of publicly funded institutes met in Washington DC this week to finalise details. They plan to have the job done within five years, and will post all the gene sequences on the web as soon as they’re available. The Global Musa Genomics Consortium will focus on discoveries that will benefit the smallholders who grow 85 per cent of the world’s bananas, mostly for their own consumption. “One rule of joining the consortium is that any invention developed through the project and protected [by patent] will be made available to smallholders through a royalty-free licence,” says Emile Frison, director of the International Network for the Improvement of Banana and Plantain, the French charity that is the driving force behind the genome effort. The sequence could be of great value to breeders and scientists, who have struggled to overcome the banana’s weird characteristics. For example, the classic Cavendish variety exported to Western countries – which is thought to have originated as a natural hybrid thousands of years ago – has three sets of chromosomes instead of two and so cannot reproduce sexually. “Half the world’s edible bananas, including the Cavendish, are entirely sterile, and you can’t breed them at all,” says Frison. Instead, they are propagated by taking the plantlets that appear at the base of old banana plants each year. Because they have been in evolutionary limbo for thousands of years, the edible varieties are particularly vulnerable to pests and disease. “Banana is one of the most heavily sprayed crops in the world,” says Frison. In Costa Rica, for example, they spray bananas roughly once a week, compared with four or five times a year for most other crops. This is why, instead of sequencing one of the edible varieties, the consortium will sequence a wild banana from east Asia. This should contain useful genes that could be added to edible varieties. For instance, a gene that protects against the black Sigatoka fungus, which ravages plantations, would be priceless. But because interbreeding is impossible, genetic modification is the only way to insert such genes into most commercial varieties. “This is one of the few crops where you could say there’s a strong justification for using GM,” Frison says. The consortium already has funding of $2 million per year, but needs a further annual $4 million. It hopes to raise this through bodies such as the US National Science Foundation and the European Union. “The establishment of a public research initiative is welcome,” says Antonio Hill of the development charity Oxfam. But the British-based charity says the researchers should examine beforehand the socio- economic impacts of new varieties to ensure they don’t end up damaging the livelihoods of the very people they’re trying to help. Frison says they won’t be seeking genes that would make bananas straight. “It would take all the fun out of bananas,

 

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