Grain Biotech harvests first salt-resistant wheat crop

Perth agbiotech company Grain Biotech Australia harvested its first trial crop of genetically modified, salt-tolerant wheat this month, grown in salt-affected farmland near Corrigin, in Western Australia.

With its extensive areas of flat, sandy soils and high water tables, a legacy of indiscriminate clearing of its native vegetation, south-western WA faces Australia's worst dryland salinity crisis.

Some 4.3 million hectares are already affected by rising saline groundwaters, and the current loss to agricultural production is estimated at AUD$300-400 million. By 2050, an estimated 8.8 million hectares will be affected -- an area equivalent in size to Tasmania.

Grain Biotech's business development manager, Alan Tough, said the trial plot, measuring only 60 x 15 metres, was completely enclosed in mesh to exclude birds. The plots were hand-harvested, and the results from each will be compared for yield and grain quality against the conventional wheat.

It was planted, with its long axis oriented down-slope on the margin of a salt scald, as 192 sub-plots, each 4m long, containing a single row of salt-tolerant wheat planted beside a single row of conventional wheat.

Rainfall in the growing season was high enough to leachy salt out of the surface zone and drain it down-slope, so Grain Biotech researchers took direct measurements of salt concentrations in the root zone from the top to the bottom of the plot.

Concentrations at the top were well below the one-third seawater optimum for the new wheat, as determined in glasshouse experiments, while Tough said salt crystals lie on the surface of the scalded area, which has salt concentrations in excess of seawater.

Apart from a bare patch halfway down-slope, the salt tolerant wheat grew all the way onto the edge of the scald, but Tough said it's not clear whether the plants managed to develop grain at this level.

Size matters

Because of the small size of the plots, it would not be possible to accurately estimate whether the salt-tolerant wheat delivered economic yields within the relatively low-salt zone, but glasshouse experiments suggested yields would be viable.

Tough downplayed expectations that the new salt tolerant wheat might be a saviour for farmers battling dryland salinity.

He said the transgene that confers salt tolerance codes for a protein that increases cellular levels of the amino acid proline cells. Proline is an osmoprotectant, which allows plants to tolerate much higher salt concentrations in their tissues.

Tough said the wheat would not remove salt from the land, but should allow farmers to continue to grow a revenue-raising crop on land that is becoming progressively salt-damaged.

Across Australia and Tasmania, the replacement of perennial native vegetation by annual cereals that transpire only six months of the year has caused the groundwater table to rise, dissolving ancient salt stored deep in the soil profile, and bringing it to the surface.

Many salt-affected agricultural regions of Australia have hypersaline groundwaters, in which salt concentrations can exceed that of seawater by a factor of 3 or 4. Virtually no terrestrial plant could tolerate such conditions; only costly engineering solutions could restore such land to production.

Under glasshouse conditions, Grain Biotech's GM wheat thrives at salt concentrations of about 30 per cent seawater -- it trumped barley, the most salt-tolerant of the major cereals, indicating it could be grown productively on the margins of saline seeps, below the 'barley line'.

Previous attempts to develop salt-tolerant cereals by integrating chromosome segments from wild grasses, but the approach has proved unfruitful because the level of salt tolerance achieved is relatively low, and genes important with the salt-tolerance loci affect grain quality and depress yields.

Tough describes it as a balancing act -- the higher the salt tolerance, the less productive the wheat, and the more likely the wheat is to suffer from quality problems.

Heading overseas

Because of the current moratoria on biotech crops in Western Australia and other wheat-growing states, Grain Biotech will probably move to commercialise its salt-tolerant wheat in the Middle East or some other wheat-growing region overseas.

Tough said Grain Biotech's efforts to commercialise specialised GM wheat varieties were being "hamstrung" by the moratoria.

"We'd like to go around the world looking for people got a good use for it," he said. "We've got a whole list of interested countries who are not opposed to GM crops.

"The GM picture not getting any clearer in Australia, and it makes funding very difficult -- if we want to release a new variety commercially, it will take three years of field trials for Australian Wheat Board to classify the variety, and then it has to be approved for human consumption by Food Standards Australia and New Zealand (FSANZ). It's a quite expensive process -- certainly more expensive than developing the wheat.

"People are entranced with what we've done, but there's no prospect of a commercial outcome for the people supporting us. We're really lucky and delighted with the role of the Grains Research and Development Corporation -- they have been very far-sighted and thoughtful in ensuring Australia is developing this sort of GM technology so we can provide some answers for the GM debate. But we're not sure that even the GRDC is getting a little deterred by the anti-GM debate."

Tough said there was little awareness of GM technology in the wide community. "We need to convince people that these crops are not designed to do weird things to them, that there are practical things we can do with gene technology that we simply can't achieve by conventional breeding," he said.

"For example, we can make wheat resistant to wheat-streak mosaic virus, which was detected last week, forcing Australia to ban imports of grain. We've already created a wheat variety with resistance to barley yellow dwarf virus, but we can't do anything with it. It's exactly the sort of problem that GM could be addressing -- there are no health or environmental overtones to that.

"We developed the BYDV-resistant wheats for Europe, where the problem is much worse than in Australia, but CSIRO recently released a report in which it concluded that BYDV is causing yield losses up to 20 per cent, even though the virus is not active.

"The anti-GM thing just freezes everything. We've got seed from our resveratrol-enhanced wheat just sitting on the shelf, and can't do anything with it."

Resveratrol, an antioxidant present in red wine, is credited as the explanation for the 'French paradox' -- the observation that French people on a high-fat diet are relatively immune to cardiovascular disease, because of the anti-oxidant effect of resveratrol in red grapes.

"We're close to being Luddites in Australia," Tough said. "There has not been a single reported case of an adverse reaction to GM food in 25 years. The debate will not be resolved in Australia. It will be resolved by our customers -- if one of our customers wants a particular type of GM wheat, we can provide it."

Tough said Grain Biotech researchers are also developing GM "pharm" wheats to produce therapeutically useful proteins in their grain, because "it seems an interesting direction to head in".

He said it should also be possible to use gene technology to modify proteins like late-maturing amylase, which causes premature sprouting in some wheat varieties before harvest, and allergenic proteins like the glutenins in bread wheat.