Archive for May, 2006
Dr Rachel Burton, Professor Geoff Fincher and a team of scientists associated with the Australian Centre for Plant Functional Genomics (ACPFG) have solved a puzzle that researchers have been working on for more than thirty years.
Their beta-glucan breakthrough was published in the March 31 issue of the journal Science. The scientists have identified a gene family, CslF, implicated in the synthesis of (1,3;1,4)-beta-D-glucans in cereals like wheat and barley. These beta-glucans are an important component of dietary fibre, and impact human and animal health, as well as the production of beer and spirits.
“This discovery means we now have the opportunity to modify beta-glucan levels in cereals, developing specialty cereals for different industries,” Dr Burton said.
“Beta-glucan is good for human health, so we can increase the levels in wheat and barley for human consumption. We can also develop low beta-glucan varieties for animal feed, because pigs and chickens can’t cope with too much beta-glucan,” she said.
The low varieties should also prove popular with breweries, because beta-glucan causes filtration problems in beer production. Beta-glucan can help prevent human health conditions like colorectal cancer, obesity, non-insulin-dependent diabetes, high serum cholesterol and cardiovascular disease. When the news of the discovery was made public, the media were particularly interested in the potential for enhanced cereal products to alleviate these medical problems.
Another possible outcome is cereal waste better suited for use as biofuel. Straw with higher betaglucan content and less cellulose may be easier to process, reducing the cost of producing fuel.
The gene discovery has not been an overnight success story. Emeritus Professor Bruce Stone from La Trobe University can attest to this.
“We first published on the biosynthesis of beta-glucan in 1973, but the biochemical route to the enzyme proved to be frustratingly difficult. Now, a generation later, using the tools of molecular genetics and gene transfer, the ACPFG team have made the breakthrough,” he said.
Professor Geoff Fincher of the University of Adelaide, with Tony Bacic and Dr Ed Newbigin of the University of Melbourne, received funding from the Grains Research and Development Corporation in 2000 to apply emerging functional genomics technologies to the problem of identifying the betaglucan synthase genes in cereals. Dr Burton began working on the project then, following on from her work on cellulose biosynthesis.
The eventual breakthrough involved comparative genomics. Dr Andrew Harvey compared a chromosomal region in barley linked to high levels of beta-glucan to the completed rice genome, identifying the CslF gene family as the most likely candidates for beta-glucan synthesis in cereals.
To test whether the CslF genes were involved, Dr Burton built vectors containing the rice CslF genes for transformation into Arabidopsis plants. Research officer Melissa Pickering transformed the plants, some of which started producing beta-glucan in their cell walls, which does not normally happen in dicotyledonous plants like Arabidopsis.
Dr Sarah Wilson used transmission electron microscopy to locate the beta-glucan in the transformed Arabidopsis plants, using a gold-labelled monoclonal antibody generated in Professor Stone’s laboratory more than a decade ago.
“This work has been a fantastic team effort by staff in South Australia and Victoria, with great synergy between the different groups,” Dr Burton said.
Dr Burton is now working on altering the levels of beta-glucan in barley plants by manipulating the CslF genes, aiming to develop grains that will be the forerunners of specialty cereals.
You can download the magazine containing this article from the ACPFG website.
I also took this photo associated with this story.