Increasing food production, lowering C emissions:

how GM can help

The continued increase in the world population (approximately 9 billion by 2050) means an increased food production is essential. This increase has to take place without adding to CO2 emissions and hence—according to the scientific consensus—exacerbating global warming. There is evidence of both elevated CO2 levels and higher temperatures adversely affecting some of the crops on which we depend. Thus, the methods used to increase production must have a significantly reduced dependence on fossil fuels.

In October 2009 the Royal Society, UK’s national academy of science, published a review of technological approaches to increasing crop yields and disease resistance—Reaping the Benefits; science and the sustainable intensification of global agriculture. Traditional methods of crossing plant varieties, organic management of soil and crops and genetic modification were evaluated. It was concluded that no single technology can solve this global problem, that the technology applied in a given situation should depend on local environmental, social and economic conditions and sometimes a combination of methods is applicable. They provide recommendations for development, including expansion of the work on genetic modification that is already underway in many research establishments across the world.

Nearly a decade ago the UK public rejected GM food, but there have been significant developments across the world since then and perhaps the time has arrived for renewed, open debate where scientists are effectively engaged with the public in explaining the relevant science and where benefits are weighed against risks.

GM compared to traditional ways of altering genomes of plants

Ever since their first cultivation, the genetic make-ups (genomes) of crops have been artificially altered by methods in which a given plant is crossed with another sufficiently closely related variant. This shuffles genes to produce offspring with much unpredictable variation. More recently, radiation techniques have also been used to cause genetic mutations within the cells of a given plant. From the variety of products resulting from either technology, desired variants are selected. Selection has been speeded up through use of molecular markers (small sections of genes that are known to be responsible for particular plant characteristics) in a screening technique called marker-assisted selection (MAS). When the genome of a particular variant contains the desired gene, it will bind to the molecular marker, which has a readily detected component.

In conventional genetic modification, specific genes are transferred from a given organism to the plant. A gene transferred from a different type of organism to the plant is known as a transgene (the process as transgenics). A gene transferred between similar organisms (e.g. between similar plants) is a cis-gene (the process cis-genics). In contrast to the traditional methods of altering genomes, the molecular techniques of GM thus allow more precision; only the specified genes coding for the desired characteristics are transferred.

Benefits of genetic modification

Genetic engineering (or modification) is a well-established biotechnology. Microbes have been genetically engineered since the 1970s to provide advances in medicine and food technology. Most insulin used today in the treatment of diabetes is human insulin that is manufactured by bacteria whose genome incorporates the insulin gene that has been transferred from humans. Cheese is made with the help of the enzyme rennet (also called chymosin); traditionally from the stomach of a slaughtered calf. Since the 1980s however, the rennet for most cheese making has come from bacteria into which the gene that informs calf cells how to make the enzyme has been transferred.

The genetic modification of plants has the potential to significantly reduce CO2 emissions by introducing genes that increase crop yields, while reducing the application of fertilisers. Disease-resistant plants have been engineered through the transfer of relevant genes that confer resistance to insects or plant viruses. This obviates the use of pesticides, which, like the fuel usually used in the planes or tractors required in their application, are derived from petroleum. To further reduce reliance on petroleum, GM plants are being developed to produce chemicals, pharmaceuticals and fuels.

Plants can be made more water-efficient through transfer of genes from drought-resistant plants, or salt-tolerant plants. Research is taking place in which genes from certain plants in arid regions that are more efficient in their use of solar energy are transferred to food crops of temperate regions, hence increasing the photosynthetic efficiency of the latter.

GM plants have been produced to enhance nutritional value; e.g. rice, with genes from a soil bacterium and from maize, produces beta-carotene which the body uses to make vitamin A. This has helped some communities in the world who have vitamin A deficiency diseases that can result in blindness.

Assessing risk

Concerns are raised about the health risk from eating GM food, about gene flow from GM to non-GM crops and the risk to genetic diversity. However, the Genetics Society, Biotechnology and Biological Sciences Research Council, Institute of Food Research, the Laws Agricultural Trust, the Institute of Biology and the John Innes Centre in Making Sense of GM, a publication that promotes public understanding of GM, conclude that there is no significant health risk from GM food, and that the risk of gene flow and of reduction in biodiversity are no greater than from conventional forms of plant breeding. The Royal Society’s report concurs. Nevertheless, they insist that each genetic modification should be thoroughly tested in laboratory and field trials before deciding whether commercial production should proceed or not. Blanket rejection of GM however, denies us a valuable means of achieving the necessary increase in food production–a risk in itself.

Organic practice alone is not without risk, since organically grown crops are susceptible to pests. Problems can be overcome through appropriate crop rotation, but GM can also help; e.g. it has been used to combat an insect that damages conventional maize, lowering yields and causing entry of fungi into cereal grains. The fungi produce mycotoxins damaging to human health. Resistance to the insect and thus increased yield is brought about through the introduction of a gene from a bacterial culture, Bacillus turingiensis (Bt). The Bt maize also has lower levels of mycotoxins than those in non-GM maize, making it safer to eat.

Conclusion

No metanarrative to explain the predicament over our food and energy problems will satisfy everyone and no single technology offers a panacea for their solution. We need an open society that considers all technologies. The Royal Society is facilitating the engagement between scientists and the public that is essential to an open debate. Reading at least their summary report and the review Making Sense of GM would help prepare us for that debate.

References

The Royal Society (2009) Reaping the Benefits

Sense About Science: Making Sense of GM

Alan Myers
21 June 2010