GM research heads to warmer climes

The old joke about Queensland being a decade plus one hour behind the southern states during daylight saving is fast fading from the repertoire of state-vs-state humour.

By decade's end -- give or take an hour -- Queensland is likely to be Australia's premier state for plant biotechnology and Australia's leading producer of GM crops.

As the southern states capitulated to pressure from anti-GM activists last year and imposed multi-year moratoria on farming of GM herbicide-tolerant canola, Queensland premier Peter Beattie was reminding Australia's dismayed agbiotech community that Queensland was still open for agbiotech business. Canola was a non-issue in Queensland; the warm climate is unsuitable for Australia's major oilseed crop.

But the Sunshine State will surely have its own night in the anti-GM spotlight, because GM versions of mainstays of Queensland's rural

economy -- sugarcane, pineapple, banana and papaw (papaya) -- are in the development pipeline.

Sweet turns sour

Australia's sugar industry is among the world's most efficient, but Brazil, the world's largest producer, has swamped the international market with cheap sugar, driving down prices and sending the Australian industry into terminal decline. Its future may hinge on 'boutique' GM sugarcane varieties modified to produce high-value industrial polymers and sugars other than sucrose.

Sugarcane is already the world's most photosynthetically efficient crop, and decades of conventional breeding have failed to produce any significant increase in sucrose yield per tonne of biomass -- the only increase has come from denser planting.

Conventional breeders were stymied by a seemingly insurmountable genetic brick wall. But Dr Robert Birch, of the University of Queensland, vaulted it in a single bound, with recombinant DNA technology.

Birch has developed several GM cultivars that produce at least twice as much sugar as conventionally bred varieties, from the same biomass.

Last year's federal government sugar industry rescue package provided only temporary respite for the beleaguered industry. If it has a future, it lies in GM varieties engineered to boost sucrose yields, or to produce high-value specialty sugars like isomaltulose and sorbitol for the food industry.

Convincing growers of the need for change will be hard enough. Countering inevitable opposition and misinformation from the anti-GM movement in the broader community will be tougher still.

Dr Peter Twine, CEO of the CRC for Sugar Industry Innovation Through Biotechnology, says the industry has a history of Investing in research, but has sometimes been slow to adopt the best outcomes from its investment. "The evidence we're now getting from research is that sugarcane can play a really important role in the carbohydrate economy," Twine says.

"For a very long time the industry has been based on a single product -- raw sugar for export. More recently it has diversified into distilling alcohol from molasses, and cogeneration of electricity from bagasse [the fibrous waste from crushed cane]. Basing your business on a single product is risky in today's economic climate. We're exploring the opportunities biotechnology offers to diversify into new products.

"The sugarcane plant is an enormously efficient absorber of carbon, and we're looking at diverting this carbon accumulation into products other than the sugar the crop was bred to produce.

"There are a range of opportunities to install enzyme systems that will divert that carbon into the synthesis of low glycaemia index sugars, alcohol, and biopolymers.

"We're also looking at using biotechnology to induce sugarcane to make more sugar, or to extract other useful compounds that are currently burned or discarded, including nutraceuticals like sugarcane wax, which reduces serum cholesterol, and flavonoid antioxidants." The industry's conservatism is potentially fertile ground for anti-GM organisations to sow doubt among cane farmers, using strategies honed in the southern canola campaign.

"I'm sure we'll get opposition," says Steven Brumbley, a senior researcher with the Bureau of Sugar Experiment Stations, in Brisbane, and a project leader with the Sugar CRC. "We've tried to go out and educate farmers and the wider community. We have a specific program in the CRC, to determine what it will take to change perceptions."

Good carbs, bad carbs

Isomaltulose is in global undersupply, and is worth up to 10 times as much as sucrose. The confectionery industry uses it as a sugar substitute. It has sugar's sweet taste, but doesn't cause dental caries because sucrose-adapted oral bacteria can't use it as an energy source.

Twine describes isomaltulose as a "low glycaemic index" sugar. It's absorbed much lower in the gut than conventional sugar, avoiding a glucose 'high' in the blood, and an accompanying surge of insulin.

Growing plastics

Queensland researchers are also experimentally inserting transgenes for bacterial enzymes into sugarcane, to produce high-value fine chemicals for industry, and the monomer precursors for biodegradable thermoplastics.

Twine said a class of biopolymers called polyhydroxalkoanates (PHAs) is enormously versatile. They can be tailored to make a huge range of plastics, including stretchy elastomers, by varying the side-branches of the backbone polymer chains, - "They could displace a large proportion of the industrial polymers made from petrochemicals," he said.

He predicts the PHA market will begin to take off this year.

Initially, all production will be via bacterial fermentation. "You have to build a $150 million fermentation plant, then feed the bacteria sugar, and the polymers end up three times more expensive than if they were made directly in the living plant.

'To get the cost down, you need to produce the precursors in plants. We think sugarcane is ideal - it's the biggest biomass crop, and these are bulk chemicals. The industry needs 2.8 billion pounds [1.27 million tonnes] of the raw material a year.

Friendly farming

Sugar production in Australia is focused within a narrow, well-watered coastal strip between environmentally sensitve rainforest and, in Queensland, the Great Barrier Reef, which is vulnerable to pesticide residues in runoff.

Dr Kerry Nutt, of the Sugar CRC, is using gene technology to tackle the industry's worst pest, cane grubs, which eat the roots of the growing cane.

Conventionally, the grubs are controlled with slow-release synthetic pesticides, or the insect-killing fungus Metarhyzium.

Installing transgenes that will synthesise species-specific insectides within the tissues of the plant, as in Bt cotton, is the way ahead. Initially, Nutt experimented with a proteinase inhibitor from tobacco, but the IP licence was too expensive.

Nutt has two experimental lines in glasshouse trials that synthesise proteins anti-metabolites that disrupt larval feeding.

She has so far been unable to find a DNA promoter to confine expression to the roots, but said if the protein pesticides work at very low concentrations, and have inherently low toxicity to vertebrates, it may be preferable to express them throughout the plant, to control a variety of pests like shoot-feeding wireworms, and leaf-feeding rhyparida beetles.

Nutt said the insect-resistant cultivars will not completely supplant synthetic pesticides, but will fit into an integrated pest management program developed to protect the environment.