Research by CSIRO to genetically modify peas to resist insect attack and reduce the use of chemical sprays has been discontinued because the GM peas did not satisfy all categories of a stringent risk assessment process.

The Deputy Chief of CSIRO Plant Industry, Dr TJ Higgins, says the findings – published this week in the Journal of Agricultural and Food Chemistry – demonstrate the effectiveness of case-by-case evaluation of GM plants and the important role science can play in decision-making around the introduction of GM crops.

The GM field peas were developed by CSIRO Plant Industry to protect Australia's $100 million field pea industry from the pea weevil Bruchus pisorum, which can cause yield losses of up to 30 per cent each year if left uncontrolled.

Although this GM breed of field pea proved almost 100 per cent effective against pea weevil attacks, research led by immunologists Dr Simon Hogan and Professor Paul Foster at the John Curtin School of Medical Research (JCSMR), with CSIRO, showed that the GM peas caused an immune response in mice.

Following discussions with the scientists conducting the study, CSIRO decided not to progress development of these GM field peas.

“This work strongly supports the need for case-by-case examination of plants developed using genetic modification and the importance of decision-making based on good science,” Dr Higgins says. 

 “Even though this GM field pea research will not be progressed further, the technology is very valuable and we're considering applying it to other research,” he says.

The CSIRO research team used a gene from beans to block the activity of alpha-amylase, an enzyme important for digestion of starch.

Weevil larvae feeding on starch in the developing pea seed are unable to digest the starch and starve.

“We asked why there was a reaction to the GM peas and not beans, which also have the alpha-amylase inhibitor, and which humans have been eating for many years without evidence of an immune response,” JCSMR's Professor Foster says.

The answer lay in subtle changes that occurred in the chemical structure of the bean alpha-amylase inhibitor when it was made in the field pea.

“The change in structure is likely to be caused by a natural and commonly occurring process called glycosylation, which occurs when proteins are made via a particular pathway in cells,” Professor Foster says.

“CSIRO had informed us that unlike other GM insect resistant plants, to make the peas insect resistant the introduced bean protein had to go through a pathway in cells where it would undergo several processing steps including glycosylation.

 “Because glycosylation is well documented and because it can differ from organism to organism and even in different cell types within an organism, we determined the structure of the pea protein, and assessed whether it was likely to cause an immune response.

“This case-by-case approach allows appropriate decisions to be made during the development of the GMO, and CSIRO has done this with its GM field peas.”

CSIRO is finalising arrangements with the Office of the Gene Technology Regulator for the disposal of GM field peas produced during the project.

1. Fact sheet at www.csiro.au/GMpeas

2. Transgenic Expression of Bean á-Amylase Inhibitor in Peas Results in Altered Structure and Immunogenicity
Vanessa E. Prescott, Peter M. Campbell, Andrew Moore, Joerg Mattes, Marc E. Rothenberg, Paul S. Foster, T. J. V. Higgins, and Simon P. Hogan
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY Volume 53, Issue 23 (November 16, 2005)
pages 9023 - 9030