martes, marzo 17, 2009

Who Can We Trust on GM Food?

  • Former chief scientist David King praises GM crops. But can we trust a government scientist any more than an industry insider?
    By Peter Melchett
    The Guardian - UK, December 9, 2008

Last week, on the Radio 4 programme Street Science, a publicist for the GM industry made a number of claims about what GM crops can do. He said: "Using GM technology, there are now varieties of major crops, rice, wheat and maize being produced that are drought resistant, flood resistant, saline resistant and disease resistant, which could transform Africa's ability to feed its people ... Some products have emerged, for example, from South Africa. They are now planting drought resistant crops that have increased the yield by 30% ... So you can actually save millions of people from starvation by these techniques - nothing to do with the private sector ... Americans are perfectly happy to eat [unlabelled GM food] and I don't know of anyone who has ever suffered from eating a GM product."

There is nothing wrong with this - similar claims are made all the time by people working for GM companies. Except that this was not Monsanto's press officer, it was Professor Sir David King, recently retired as the UK government's chief scientist.

The first claim, if read carefully, is not inaccurate. GM companies are trying to produce crops that are drought, flood and saline resistant, and although none are available for commercial use, in theory such crops could increase food production in Africa and elsewhere - if you make a number of assumptions.

These assumptions are not scientific, they are political, subjective and highly contested. This particular point of view assumes that the key cause of hunger and starvation is lack of food, rather than problems with distribution, access to land, wars, corruption and poverty. It also assumes that in future poor farmers will have no problems with buying expensive seeds, fertiliser and pesticides, all of which are required by GM crops. I know many people assume GM crops must somehow be needed to feed the world. But the IAASTD (the food and farming equivalent to the Intergovernmental Panel on Climate Change) report by 400 international scientists - led by Professor Robert Watson, now chief scientist at the Department of Environment, Food and Rural Affairs - said GM crops were not essential to feed the world.

David King was wrong to say that drought-resistant GM products that increase yield by 30% are now being planted in South Africa. In fact, Monsanto is carrying out trials of GM drought-resistant maize in South Africa. The process of trialling the crops has only just begun (a permit was issued a year ago), and these crops are probably about eight years away from commercial use if they prove to be successful. No drought-resistant GM crops are currently grown commercially in South Africa. King has been wrong before about new crops in Africa, claiming that a successful project near Lake Victoria was benefiting from GM technology, before having to admit the crops involved were not GM at all.

In the BBC programme, David King referred to crops like rice that are "flood resistant". In fact the submergence tolerant (flood resistant) rice that is on the market is not GM, but instead marker assisted selection (MAS), normal breeding informed by knowledge of the genome and supported by environmentalists and organic organisations, was used to develop it. This is an example of the kind innovative non-GM plant breeding that is making a lot of progress in a number of areas that the GM companies are only just beginning to tackle - with unknown results. Marker-assisted breeding (usually called marker assisted selection) uses the genetic diversity found in crops or their wild relatives, combined with genomic data (genomic markers) to speed up what are otherwise essentially conventional breeding methods.

Two years ago, the scientists at the University of California Davis responsible for developing submergence tolerant rice initially tried to develop the rice using both MAS and GM techniques. While the MAS worked well and quickly, GM failed initially, for unknown reasons. The scientists were moving a rice gene into another type of rice, so this failure simply underlines the inherent uncertainty and lack of precision in GM technology. Finally, a couple months ago, the scientists did get the GM process to work, but this version is not being bred for sale to farmers. To get the GM process to work, the scientists had to attach the gene they wanted to transfer to a very powerful promoter - the part of the gene that determines in what parts of the plant, when, and how much, the gene functions (called "expression"). The promoter they used is from an ubiquitin gene and it is turned on at a high level in many tissues of the plant, most of the time.

This contrasts with the normal (native) promoter of the sub1A gene, which is turned on only when needed in the plants and at the correct levels. Therefore, while the sub1A gene, run by the ubi promoter may nominally function, it is much more likely to have negative side effects in the plant because of its incorrect expression (called ectopic expression). These effects could be harmful to health or the environment, or just have adverse effects on the agronomic properties of the crop (for example, it could cause the crop to grow poorly under some conditions, as has happened in practice with some other GM crops). Normal breeding using MAS worked better and faster, and is less likely to have negative side effects.

David King also mentioned GM crops that "have not been produced in the private sector, they've all been produced by government and international research laboratories" when he spoke about crops being developed for farming in South Africa. I assume that he was actually talking about the Water Efficient Maize for Africa project (WEMA), which involves several African countries - Kenya, Uganda, Tanzania, and South Africa. The WEMA project was only announced in 2008, so no crops have yet been grown even experimentally. The projections for yield increases from this project are that "the maize products developed over the next 10 years could increase yields by 20-35% under moderate drought, compared to current varieties". But this applies to non-GM as well as possible GM varieties, and the first conventional varieties developed by WEMA could be available after six to seven years of research and development. The project says that GM drought-tolerant maize hybrids "will be available in about ten years".

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