CSIRO has developed a new experimental wheat variety with the potential to provide benefits in the areas of bowel health, diabetes and obesity.

In a paper published today in the international science journal, Proceedings of the National Academy of Sciences, researchers working within the Food Futures Flagship describe how they used CSIRO-developed RNAi gene silencing techniques to suppress the expression of two starch-branching enzymes in an experimental wheat.
 
‘The wheat had a significantly altered starch composition, increasing the amount of amylose from about 25 to 70 per cent,’ Theme Leader, Dr Matthew Morell, says.

‘Amylose is a form of starch that is more resistant to digestion, providing the potential for the new wheat to be an important component of foods with a low glycaemic index. Starch resistant to digestion is also expected to generate favourable changes in the gastro-intestinal tract that promote bowel health and would be expected to lead to a reduction in colorectal cancer risk.’

An animal trial confirmed that there were positive changes in indicators of bowel health in rats fed a diet of the high-amylose wheat, when compared to standard wheat. Importantly, there was no change in the growth rate of the rats.
 
‘The use of gene technology has proved exceptionally useful in defining the genetic changes in wheat that are required to generate this new type of wheat,’ says Dr Morell. ‘The team’s current task is to breed the wheat using conventional methods, instead of gene technology. By using molecular marker technology we are now able to identify the genetic diversity necessary to develop high amylose wheats using conventional breeding.’

Food Futures Flagship Director, Dr Bruce Lee, says the Flagship, working with CSIRO Plant Industry, Human Nutrition and Food Science Australia – and its French partner, Biogemma – is developing novel wheat varieties to meet the community's emerging health needs.

‘Diet-related non-infectious diseases, such as colo-rectal cancer, heart disease and diabetes, are some of the most serious health problems in the developed world,’ Dr Lee says. ‘They are major causes of premature death and disability and pose a serious economic and social burden.

‘These new wheats produce significant levels of resistant starch. They can be incorporated as wholegrain into breads, cereals and other foods, giving us the opportunity to improve human health.’

Biogemma’s General Manager, Michel Debrand, says the outcome shows how the development of a health benefit, which adds value to seed grain, can result from long-term partnerships between CSIRO and companies like Biogemma.

‘It’s an example of how different aspects of biotechnology, including gene discovery and genetic transformation, can be used to uncover biodiversity in a way which delivers real benefits to the consumer,’ Mr Debrand says.

The paper: ‘High-amylose wheat generated by RNA interference improves indices of large-bowel health in rats’ appears in the 27 February, 2006, edition of  Proceedings of the National Academy of Sciences, and can be viewed at: http://www.pnas.org/papbyrecent.shtml