The world's first cotton plants genetically modified to produce healthier cooking oils and margarines have been developed by CSIRO Plant Industry.

Cottonseed oil is already used extensively as an ingredient in margarines and cooking oils, particularly in the food service sector.

However, to make it suitable for these uses it is generally subjected to a process known as 'hydrogenation' which can produce cholesterol-raising trans fatty acids as a by-product.

"Oil from our improved cottonseed is suitable for cooking purposes without the need for hydrogenation," says Dr Allan Green, leader of the research team.

"Products made from these oils will be healthier because they will not contain trans fatty acids."

To produce the new oils, the scientists 'switched off' genes in cottonseed that normally convert oleic acid, a monounsaturated fatty acid, into polyunsaturated fatty acids. Polyunsaturates are nutritionally valuable, but break down under extreme heat, making them unsuitable for cooking uses.

"The hydrogenation process converts the polyunsaturates back into monounsaturates, but we have prevented their formation in the first place," says Dr Qing Liu, the scientist who genetically modified the cotton.

"By turning off the gene that produces polyunsaturates we have produced for the first time an inherently high-oleic cottonseed oil.

"We haven't added any foreign genes to the cotton to achieve this, but have reintroduced a very small amount of the cotton plant's own DNA."

The healthy high oleic cottonseed oil will remain stable under high temperatures, making it a suitable replacement for hydrogenated oils and saturated oils in food service applications.

In a related development, the CSIRO research team has also successfully used gene technology to alter the proportions of saturated fatty acids in cottonseed oil. Saturated fatty acids provide the solid properties that make cottonseed oil useful in margarine production.

About a quarter of cottonseed oil is made up of two saturated fatty acids, called palmitate and stearate. Conventional cottonseed contains mostly palmitate, with small amounts of stearate. Nutritionists believe that stearate does not raise blood cholesterol, but palmitate does.

Dr Liu has modified the cottonseed so that it produces stearate instead of palmitate, making it a healthier product for margarines.

"Preliminary testing of the high oleic and high stearic oils will be undertaken by Food Science Australia at the end of the year," says Dr Green.

"Following successful completion of the product testing and approvals from the Office of the Gene Technology Regulator, work will begin on developing commercial varieties of the genetically modified cottons."

The first field trials could commence in 2002. If all progresses well, commercial varieties could be available to growers by 2004 with the first commercial harvest in 2005.

"This development will ultimately help the Australian food industry replace our $50 million annual imports of palm oils with healthier, locally produced oils," says Dr Green.

"The improvement in nutritional value of our food oils is an example of how gene technology can be used to provide consumer benefits not achievable with conventional breeding approaches."

All CSIRO Plant Industry gene technology research is conducted according to guidelines set down by the Federal Government's Genetic Manipulation Advisory Committee.

This research is supported by cotton growers through the Cotton Research and Development Corporation.

Photographs available on request or from: www.pi.csiro.au/Media/MediaReleases/MediaReleases.htm

More information from:

Dr Allan Green, CSIRO Plant Industry 02 6246 5154

Dr Qing Liu, CSIRO Plant Industry 02 6246 4919

Sophie Clayton 02 6246 5139, 0418 626 860, sophie.clayton@pi.csiro.au