Australian researchers have crossed a modern wheat variety with a wild ancestral cousin to produce a high-yielding salt-tolerant plant that will help tackle world food shortages due to soil salinity.

Matthew Gilliham, of the University of Adelaide, said the new variety of durum wheat would be made freely available to publicly funded breeding programs overseas. Field trials in Moree and at other sites across southern Australia have shown that the new variety has a grain yield in salty soil of up to 25 per cent higher than that of the standard variety.

Dr Gilliham said that this was the first study in the world to demonstrate on a farm, not just in the laboratory or greenhouse, that a new salt-tolerant wheat had improved yield. “This is why this work is particularly important, we think,” he said. The results of the fifteen years of efforts are published in the Nature Biotechnology journal today.

The team first identified a gene in an ancestral salt-tolerant relative of commercial durum wheat that removes sodium from water as it is transported from the roots to the leaves. Gilliham said when salt accumulates under in the leaves of wheat, it becomes toxic and reduces the plant yield. “We have identified a gene from an ancestor of modern wheat that when inserted into a modern commercial variety of wheat improves its salinity tolerance in the field in terms of grain yield by up to 25 per cent…This gene functions by preventing the salt from the soil getting up into the leaves of the plant,” he said.

Dr Gilliham said their challenge was then to develop a new cross-breed which had this gene, without reducing the crop yield. Field tests showed the new hybrid performed the same under normal conditions as the commercial wheat without the gene, but outperformed it under salty conditions.

Team member Rana Munns, of CSIRO, said salinity, which affected more than 20 per cent of the world's agricultural soils, posed an increasing threat to food production due to climate change. “It's currently estimated that about 69 per cent of the Australian wheat belt is affected by salinity, and currently about 11 per cent of the total agricultural land in Australia is affected by salinity,” Gilliham said. “This figure is predicted to rise to about 34 per cent in the next 38 years due to the affects of climate change. Salinity is also a problem in many areas of the world that have a similar climate to Australia,” he said. But salinity can also be a problem in irrigated agriculture - which produces about 30 per cent of the world's food needs - if crops are irrigated with water that contains salt. “With global population estimated to reach 9 billion by 2050, and the demand for food expected to rise by 100 per cent in this time, salt-tolerant crops will be an important tool to ensure future food security,” Gilliham said.

A new variety of bread-making wheat with the salt tolerance gene is also being developed by the team. “The potential gains for bread wheat will hopefully also be significant,” Dr Gilliham said. “Obviously bread wheat is a much larger crop than durum wheat. The great thing about improving the salinity tolerance of durum wheat - certainly for Australian farmers - is that there is a premium for durum wheat,” Durum wheat is used to make pasta and couscous. He said durum wheat has already entered breeding programs and he hopes a commercially available wheat will be available in under five years.

“Now we've identified the gene we can also use GM technologies to transfer this gene across to other species as well,” he said. “So this may improve not only the salinity tolerance of wheat but also of other crop plants.”

The research has had support from the Australian Centre for Plant Functional Genomics, the Australian Research Council and the Grains Research and Development Corporation.