"These results highlight the obstacles in removing certain plant allergenic proteins that perform essential cellular housekeeping functions."
Allergen-free GM plants may boost food safety: experts
By Stephen Daniells
Advances in the field of genetic engineering may produce plants with little or no allergens, but there are limits to this approach, say Australian researchers.
Genetic modification of plants and crops has long been touted as a means of producing hypoallergenic foods, but real progress in this area is limited by overcoming the "essential requirement for some of the major allergenic proteins for normal plant function," wrote Mohan Singh and Prem Bhalla from the University of Melbourne.
"It is very unlikely that plant foods can be engineered to be completely free of allergens, but the removal of a few immunodominant allergens might reduce the severity of allergic reactions, substantially improving the safety of foods," they add in the journal Trends in Plant Science.
"It is hoped that, over time, hypoallergenic food products from genetically engineered plants will reach market shelves."
Food allergy is an area of growing concern for the industry and the public. According to the Food Allergy and Anaphylaxis Network, over 12 million Americans have food allergies, equivalent to four percent of the population.
Allergies to milk, eggs, peanuts, tree nuts, soy, fish, shellfish, and account for 90 percent of all food-allergic reactions in the US, says the network.
In the new research focus, Singh and Bhalla from the Australian Research Council Centre of Excellence for Integrative Legume Research at the University of Melbourne review the potential of genetic engineering to produce hypoallergenic plants.
Significant research has focused on removing the allergens from peanuts, as these can be deadly. The science has focused on three types of proteins: Ara h1, h2, and h3.
"Of these three allergenic proteins, the Ara h 2 glycoprotein is the most potent allergen, with nearly 50-fold greater potency than Ara h 1," wrote Singh and Bhalla.
Using gene silencing techniques, researchers have reported the production of peanut plants with virtually no Ara h2, said the reviewers.
Another plant that has received research attention is the humble tomato, said the Melbourne-based scientists. In this case, the goal has been to remove the ns-LTP protein from the fruit.
Despite advances in producing plants with ns-LTP suppression, other allergens exist in tomatoes that have evaded modification. The allergenic proteins, Lyc e 1, Lyc e 2 and Lyc c 3. Lyc e 1 are associated with profilin, a ubiquitous protein found in all eukaryotic cells, and essential for plant cell function. Attempts to modify the genes that produce these proteins have been unsuccessful, said Singh and Bhalla.
"The transgenic plants exhibited severe growth retardation along with yield reduction, however, and some transgenic lines did not bear any fruit.
"These results highlight the obstacles in removing certain plant allergenic proteins that perform essential cellular housekeeping functions," they added.
Improving the image of GM
"The availability of foods with enhanced safety profiles might help to increase the consumer acceptability of genetic engineering," wrote Singh and Bhalla.
"Genetically engineered hypoallergenic plants might one day be established as a useful adjunct to allergen avoidance as a strategy for the management of food allergy symptoms," they concluded.
All food allergies gone within a decade?
In 2006, Dutch researchers told the BA Festival of Science in England that food allergies could be consigned to the history books within a decade if the combination of biotechnology and vaccines work as planned.
Dr. Ronald van Ree from the University of Amsterdam told attendees in Norwich that the key finding of the research presented was: A clever combination of biotechnology (hypo-allergenic recombinant allergens) and vaccine-development (novel adjuvants based on anti-inflammatory molecules from pathogens) [to] provide new tools to treat food allergy.
Despite offering a potentially life-saving solution for millions around the world, acceptance of GM peanuts is not guaranteed. The GM tag continues to be one of the biggest challenges for consumer acceptance, particularly in Europe and most notably in the UK.
Source: Trends in Plant Science
June 2008, Volume 13, Issue 6, Pages 257-260
"Genetic engineering for removing food allergens from plants"
Authors: M.B. Singh, P.L. Bhalla
EXTRACT: "The transgenic plants exhibited severe growth retardation along with yield reduction, however, and some transgenic lines did not bear any fruit.