Gene genies

18 February 2010

Opening spread of Gene genies featureWild corn is sorry looking stuff. It’s hard to tell it from a weed at first glance and, as University of Cambridge plant scientist Jim Haseloff points out, that’s not a surprise. “Most crop species are weedy species that have been through selective breeding processes over the past 10,000 years,” he says.

The Earth is host to some 20,000 known edible plant species out of an estimated quarter million species in total. Of that 20,000 a mere 10 per cent are grown in any volume by farmers. And just three account for the bulk of the biomass we actually eat, says Haseloff: rice; corn; and wheat.

Genetically, there is not very much difference between wild corn and what farmers plant today, even after the revolution in yields provided by hybrid corn and other crops developed during the Green Revolution of the mid-20th Century. It may seem churlish to make this point but plants are quite inefficient at converting sunlight and carbon dioxide into the carbon skeleton needed to grow roots and leaves. RuBisCO, a protein complex that lies at the heart of the photosynthesis process, is notoriously inefficient as an enzyme, although some researchers argue that RuBisCO is about as good as it can get.

RuBisCO evolved in a very different atmosphere to the one that the Earth today possesses – largely thanks to the descendants of the first organism to make RuBisCO. That early atmosphere was loaded with carbon dioxide. A form of RuBisCO reworked to cope better with an oxygen-rich atmosphere could lead to much faster growing, high-yielding plants. Ideas like this encourage researchers to look much more closely at how plants and crops grow. Haseloff’s work, for example, concentrates on the way that plants regulate their growth in the hope of using new DNA to maximise the production of the edible parts.

Optimising plant yield is vital according to a growing number of politicians who, having spent years in Europe at least negotiating over ways to stop farmers growing things are now issuing warnings about “food security” as the global population continues its relentless surge towards 9 billion people on the planet by 2050.

At the Oxford Farming Conference at the beginning of the year, UK secretary of state for the environment, food and rural affairs Hilary Benn said: “Food security is as important to this country’s wellbeing – and that of the world’s – as energy security. Securing both must be our priority.”

UK Government chief scientist John Beddington declared at the Oxford Farming Conference: “We need a new and Greener Revolution, improving production and efficiency through the food chain within environmental and other constraints. Techniques and technologies from many disciplines, ranging from biotechnology and engineering to newer fields such as nanotechnology, will be needed.”

Theodor Friedrich, an agriculture expert with the FAO says: “With our conventional way of going about agriculture we are facing limitations. Production is not keeping pace with population. Our traditional approach to agriculture is reaching a ceiling – we hit a wall.”

Some conventional techniques turn out to be counter-productive, says Friedrich: “In tropical countries by applying more fertiliser, the yields actually go down.”

Other means are needed. Beddington said research could aim for ambitious goals of improving not just nitrogen fixation by plants but the photosynthentic potential of crops. The changes could be through more efficient, reworked enzymes such as RuBisCO. “These are likely to be global in nature and give the UK research base an opportunity to engage in cutting-edge research with other key global players.”

But that cutting-edge research might never make it to market. For more than ten years, European Union states have presided over a situation where genetically modified (GM) crops are potentially legal but rarely used.

Reticence to apply GM goes way beyond Europe. The FAO World Summit on Food Security held last November had no mention of GM on its agenda, a very different stance from that taken when the FAO published its 2004 State of Food and Agriculture report, in which the organisation said it supported the use of biotechnology. It was a move that prompted a letter from 800 representatives of a variety of non-governmental organisations (NGOs) to write a letter to FAO director general Jacques Diouf.

The report Food Security and Agricultural Mitigation in Developing Countries makes no mention of GM or other genetic-engineering techniques, although an earlier report on technology prepared for the autumn High-Level Expert Forum in Rome said GM might be a component of future food development. The report warned its potential advantages had to be weighed against public opposition.

In the closing press conference of the Food Security Summit also held in Rome, Diouf did not address GM directly but said talks at the conference did focus on “the contribution of technology to agricultural development, to research resistant varieties, that will deal with stress and drought particularly in the framework of climate change, salinity or whatever”.

Improved food production would revolve around an effort that combines many techniques, he added: “We therefore needed to bring research organisations together to discuss this”.

The reticence among the public to embrace GM may help improve its performance, which has been patchy. David Dawe, senior food systems economist with the FAO says one of the problems with technology is that it can focus too readily on large farming operations and take a long time to put into action properly. “For the small farmer, if it takes years of learning, it’s no use to him.”

There are other problems with commercial GM crops, which so far have focused on herbicide tolerance and pest control and which tend to suit the large plantations found in the US and South America. For example, crops augmented with the Bt gene produce a protein that kills caterpillars that would otherwise feed on them. Roundup Ready crops developed by Monsanto are engineered to not be affected by the company’s own weedkiller.

Christian Fatokun, geneticist at the Nigeria-based International Institute of Tropical Agriculture (IITA), says: “Some of the GM [crops] in use today may not be particularly attractive to Africa, for example, if you may take a crop like Roundup Ready soybean. Here, in Africa, you see farmers growing soybean with other crops in the field.

“So, if you spray Roundup, you are going to kill the crops – only soybean will remain. Nobody wants that kind of tech,” says Fatokun. “But there are crops that are useful in Africa and those are the ones to which we should give trials to see how they can be of benefit to farmers, the consumers and the communities as well.”

For many tropical farmers, blockbuster engineered crops are not the answer. Boru Douthwaite, impact and adoption specialist with the IITA, uses an example from the Green Revolution where one variety of rice wound up being planted on some 11 million hectares, “making it the most widely planted rice variety ever. However, problems emerged when millions of rice farmers all moved from growing a number of their traditional varieties to just one or two genetically homogeneous varieties. Some of the resistance that the breeders had given the improved varieties against pests and diseases broke down within three to five years, leading to huge crop lossses”.

Douthwaite explains: “In evolutionary terms, the cause of the problems was not with the novelties per se, but with the selection and diffusion mechanisms that led to them to be adopted so widely without considering the consequences. This has been a salutary lesson: reductionist science that isolates problems and ignores contexts and scale issues can come horribly unstuck even in relatively simple ecosystems.”

Work carried out by groups such as the IITA, many of which cooperate through the Consultative Group on International Agricultural Research (CGIAR) has shifted away from trying to apply single techniques and to find ways to get farmers to adopt only the ones that work on their own fields. Rather than supply huge quantities of seeds direct, the aim is to produce plants with the right traits that can then be cross-bred with suitable local species.

Caroline Herron, a scientist working at the IITA Tanzania, says biotechnology “is probably the only way we can get true resistance” to the brown streak disease that afflicts cassava. This project received in January a $2.4m grant from the Bill and Melinda Gates Foundation to use a technique called marker-assisted selection to help breeders make sure the local seeds they produce have the right resistance traits.

As a geneticist at Duke University, Professor Thomas Mitchell-Olds is working on drought-resistant rice that will use a similar distribution mechanism: “My focus is on natural variation. I work with breeders one the one hand and lab biologists on the other to understand how we can improve production for small farmers.”

GM on its own is unlikely to hold the answer to crops that are more productive in the long term. But the focus on GM versus non-GM is a potentially damaging view. As Professor Douglas Kell, chief executive of the Biotechnology and Biological Sciences Research Council, explained to MPs from the Science and Technology Select Committee in January: “We need a changed regulatory regime. We need to be basing regulation on the agricultural results themselves, not the method by which they are produced.”

This feature formed part of a special issue on food in Engineering & Technology. You can read more at the IET site.

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