Raise your glasses to biotech
Thursday, 05 December, 2002
The future is hammering on the ancient oak doors of two of the world's oldest biotechnology industries, beer and winemaking, both citadels of tradition and conservatism.
In Australia, the wine industry is wide awake, and cautiously surveying the landscape for longer-term opportunities emerging from gene technology. The Australian wine industry, which has transformed itself during the past 30 years with a slew of innovations in viticulture, and new winemaking technologies, is enjoying the first fruits of the gene technology revolution -- but is in no hurry to grow GM vines.
CSIRO Plant Industry molecular geneticists produced the world's first transgenic grapevine in 1996. One of the scientists involved in its development, Dr Nigel Scott, says he doesn't see transgenic vines coming into the viticulture industry until there is universal acceptance of GM agriculture around the world.
"The drive for GM is coming from annual field crops. Ours is a perennial crop that grows for a century or more, so we have to be confident in what we are doing," he says.
Dr Jim Hardie, director of the Cooperative Research Centre for Viticulture, at Glen Osmond, Adelaide, says the Australian industry is using gene technology to "understand the plant a bit better."
The industry -- and more pertinently, international markets -- is not yet ready for genetically engineered novelties. The power of the technology lies in being able to study gene function in traditional varieties, says Hardie. DNA fingerprinting techniques developed by CSIRO have also proved very useful for resolving the identity of some of the more obscure varieties or variants that have found their way into Australian vineyards over the past two centuries. "The stuff that excites me is the use of DNA microarray technology to see which genes are turned on or off at critical stages of grape development," Hardie says.
Hardie believes there is enormous scope for investigating stress responses in vines, which are the source of most of the flavouring compounds in wine. "These compounds are either there to protect the fruit, or to improve the dispersal of seeds, so vines are likely to be responding to environmental cues in very subtle ways," he says. "We have learned that tannins begin forming much earlier that anyone thought, at flowering." Tannins, which give red wines their body and 'feel' in the mouth, inhibit feeding in insects.
"It makes sense that tannins are being produced during flowering and early berry development, because this is when the seeds begin to form, and the plant has a big investment in protecting its seeds."
Hardie says the Viticulture CRC, whose research members include the Australian Wine Research Institute, the University of Adelaide, CSIRO Plant Industry, and the South Australian Agricultural Research and Development Institute, is trying to determine which tannin fractions are most important to grape and wine quality.
"We're working to identify the genes in the tannin synthesis pathway, trying to understand their contributions to sensory impact," he says. "Once we know which genes are involved, and when they switch on or off, we should be able to optimise tannin chemistry through better management back at the vineyard. We could also manage white grapes to minimise tannins, which are undesirable in most white wines."
South Australian research
Much of Australia's wine research is based in South Australia -- a state where the Australian Democrats are leading a campaign for a moratorium on GM crops. "The campaign aims to make South Australia GM-free within five years," Hardie says. "We're developing plants that may not be ready for 10 to 20 years, but the SA wine industry wants to be a part of it.
"An interesting thing is that we have even had support from a well-known organic grape grower and winemaker, who believes it will reduce the need for chemicals." Hardie says CSIRO vine geneticist Dr Mark Thomas is chairman of an International Grapevine Genome Program which involves collaboration between grape genomic researchers of the major winemaking countries. The aim is to produce improved plants using genomics technology, but the industry's uptake of these plants is likely to take a while.
"The problem is that it's a terribly conservative industry, and new varieties don't go down that well. Nobody makes a fortune out of them," he says. "But as the market becomes more competitive, we expect there will be increased pressure to improve quality, and productivity, as well as for regional product differentiation."
Room for improvement
CSIRO's Scott says there is still vast room for improvement and innovation in the industry. He says there is "enormous" genetic diversity in Vitis vinifera, and the potential to create new varieties to rival or trump bluebloods like Cabernet Sauvignon, Chardonnay and Riesling.
The question is whether an industry steeped in centuries of tradition, and skilled in conjuring such a wealth of sensory riches from a limited number of traditional varieties, will accept novelty and greater diversity.But Scott and his colleagues see enormous promise in using gene technology merely to investigate the mechanisms that give rise to such richness.
The future resides in the biological equation P = G+E, which states that a organism is the product of the interaction between its genes and its environment.Scott observes that no horticultural industry has a greater interest in the effect of 'E' on the quality and quantity of its product, but the 'G' term has been a black box for more than 6000 years. Scott says gene technology is the key to the black box.Understand how vines respond to their environment, and you revolutionise vine management, and lift the already high standard of Australian vines -- no new genes required.
A combination of virulent anti-GM sentiment, and the wine industry's own deep conservatism in its traditional European heartland are stifling the application of gene technology. Australia can exploit its leadership in vine genetics to make giant steps where others currently fear to tread. As a striking example, says Scott, his team is closing in on a resistance gene for the wine industry's ancient nemesis, powdery mildew.
No wild or domesticated grape variety is resistant to powdery mildew, so French geneticists crossed Vitis vinifera with a North American cousin, Muscadinia rotundifolia. Some of the intrageneric hybrids exhibited resistance to powdery mildew. By back-crossing the hybrids to Vitis, Scott and CSIRO colleague Dr Ian Dry have shown the resistance trait probably involves a single gene, Run-1 (Resistance to Uncinula necator). They know approximately where the gene resides, and are closing in on it with DNA markers.
Scott believes Run-1 could be one of the most valuable plant genes yet discovered. The global viticulture industry sprays huge quantities of costly fungicides on vineyards to control powdery mildew, and European consumers are as averse to pesticide residues in their food and wine as they are to GM foods.The dilemma for the industry is the gene could eliminate spraying for powdery mildew, protecting the environment and soothing consumer concerns over pesticide contamination, but gene technology is the only way to introduce the Run-1 gene into the traditional varieties that have been the mainstay of global wine production for centuries. Hybridisation would contaminate these blueblood lines with thousands of mongrel genes.
Scott says countries like France have a far more serious problem with powdery mildew than Australia, because the fungus has been present in Europe longer, and there are more races to contend with. DNA markers developed by Scott and Thomas for fingerprinting vine varieties have already highlighted the hazards of hubris in a highly competitive global market.
Using CSIRO's microsatellite markers, researchers at the University of California, Davis, revealed that the premium white wine variety Chardonnay arose as a chance hybrid between the venerable vin Roman variety Pinot, and the vin ordinaire white variety Gouais Blanc. French winemakers were surprised and chagrined to learn that their number one red, Cabernet Sauvignon, is a hybrid between Sauvignon Blanc and a rustic red, Cabernet Franc. Since 1930, all hybrids have been excluded from the prestigious Appellation d'Origine Controlle (AOC) scheme, and the viticulturalists have worked exclusively with elite varieties -- a policy that has probably cost the French wine industry decades of progress.
Despite Europe's aversion to all things GM, Scott says winemaking nations like France, Germany, Hungary, and Italy are all producing and testing transgenic vines -- but much of the work is focused not on wine grapes, but on developing new, seedless table grapes with higher sucrose levels and attractive colours.
CSIRO's Thomas has discovered a golden gene in Pinot Meunier: a dwarfing gene that causes vines to grow less vigorously, but to produce more fruit. Scott says Pinot Meunier is actually a chimera -- it contains the complete genomes of two different varieties. "Mark has separated them -- one looks like Pinot Noir, the other has a very low habit, growing almost like a ground cover," Scott says.
"It has a very short internode length, and where most young vines grow tendrils from their nodes for the first one or two years, without producing fruiting buds, the dwarfing gene induces flowering and fruiting within three months of the plant shooting. Like the dwarf rice and wheat varieties that powered the 'green revolution', and popular dwarf apple, peach and nectarine cultivars, the mutation results in insensitivity to the plant growth hormone giberellic acid (GA).
Genetic and physiological markers are beginning to have an impact on vine breeding, says Scott: "In the past, we used to cross things without much purpose, and then wander down into the paddock a year later and see what we had." CSIRO breeders have recently delivered four new purpose-bred rootstocks for the wine industry to experiment with.
"The industry's prime requirements in a rootstock are lots of wood, long, straight stems, cuttings that root easily and graft well, and are compatible with Vitis vinifera. They also should not affect the oenological qualities of the grape.
"All the rootstocks currently used in Australia are American hybrids," Scott says. "They're pretty vigorous, and tend to pump up the vine too much, resulting in lots of vegetative growth and vigour. We haven't really worked out a way to manage them."
The new CSIRO hybrid rootstocks were bred primarily for desirable physical characteristics, as well as for resistance to phylloxera and nematodes, and salt tolerance. But they also produce lower levels of potassium, reducing scion vigour. Tests with Shiraz scions have shown that they give rise to grapes of good colour and excellent winemaking properties.
Gene technology will have its biggest impact as a diagnostic and management tool, allowing growers to monitor crop growth and development, Scott believes. "If we can find particular genes that are really responsive to management, and others that will enable early prediction of yield and quality, we will be able to go out, sample the buds, determine how many are going to produce flowers, determine how much we want to prune to maintain quality, or make management decisions in response to weather conditions.
"We can then plug this crop prediction and crop management information into a decision-support system for the grower -- GM vines are really just the tip of an enormous iceberg of genetic information that will enable us to grow better vines, and make better wines -- it will be marvellous for the industry."
Going with the grain
In contrast to the wine industry, the brewing industry has pulled up the drawbridge to wait out the anti-gene technology siege in the food and beverage industries.
"Go back 15 years, and the brewing industry thought gene technology was going to offer great things," says Carlton and United Breweries' Terry Kavanagh, chairman of the Australian Association of Brewers.
"Many big brewers like Carlsberg, Asahi, Miller and Annheiser Busch were interested. But as it stands now, I know of no brewery in the world actively pursuing [genetically modified] projects for raw materials used in brewing, like barley, yeast and sugar.
"That's not to say they won't be supportive of things that may be done in the future. Our technical people believe it offers quite significant benefits. But those that have worked on things like yeast have stored it away. The Australian industry's view is that we won't use GM until all the environment, safety and health issues are resolved.
"That leaves aside the technology relating to analytical methods not directly involved in brewing, such as using gene probes to see what is happening in yeast cells -- we would use them if we thought they were beneficial."
Pat Goddard, marketing and product manager for Lion Nathan, which owns the Tooheys and Hahn brands, says the Australian brewing industry also will not risk using sugar from new transgenic cane varieties being developed for increased sucrose production, or resistance to disease.
Through the 1990s, the brewing industry helped sponsor a project at CSIRO Plant Industry in Canberra to develop new barley varieties with increased content of starch and analyse, the enzyme that converts starch to sugars during the malting process.
The project met its objectives, and barley, like rice and maize, can now be genetically transformed with the plant geneticist's standard gene-delivery agent, Agrobacterium tumefaciens. But the industry, nervous about anti-GM sentiment, withdrew funding, and CSIRO wound up the project.
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