Using non-GM crop breeding techniques, scientists from CSIRO Plant Industry introduced a salt-tolerant gene into a commercial durum wheat, with results shown in field tests. Researchers at the University of Adelaide’s Waite Research Institute led the effort to understand how the gene delivers salinity tolerance to the plants.

The research is the first of its kind fully to describe the improvement in salt tolerance of an agricultural crop—from understanding the function of the salt-tolerant genes in the lab, to demonstrating increased grain yields in the field.

The results are published in the journal Nature Biotechnology. The paper’s senior author is Dr. Matthew Gilliham from the University of Adelaide’s Waite Research Institute and the ARC Centre of Excellence in Plant Energy Biology. Lead authors are CSIRO Plant Industry scientists Dr. Rana Munns and Dr. Richard James and University of Adelaide student Bo Xu.

This work is significant as salinity already affects over 20% of the world's agricultural soils, and salinity poses an increasing threat to food production due to climate change.Dr. Rana Munns

Domestication and breeding has narrowed the gene pool of modern wheat, leaving it susceptible to environmental stress. Durum wheat, used for making such food products as pasta and couscous, is particularly susceptible to soil salinity.

However, the authors of this study realized that wild relatives of modern-day wheat remain a significant source of genes for a range of traits, including salinity tolerance. They discovered the new salt-tolerant gene in an ancestral cousin of modern-day wheat, Triticum monococcum.

Salty soils are a major problem because if sodium starts to build up in the leaves it will affect important processes such as photosynthesis, which is critical to the plant’s success. The salt-tolerant gene (known as TmHKT1;5-A) works by excluding sodium from the leaves. It produces a protein that removes the sodium from the cells lining the xylem, which are the pipes plants use to move water from their roots to their leaves.

—Dr. Matthew Gilliham

Field trials were conducted at a variety of sites across Australia, including a commercial farm in northern New South Wales.

Importantly, there was no yield penalty with this gene. Under standard conditions, the wheat containing the salt-tolerance gene performed the same in the field as durum that did not have the gene. But under salty conditions, it outperformed its durum wheat parent, with increased yields of up to 25%. This is very important for farmers, because it means they would only need to plant one type of seed in a paddock that may have some salty sections. The salt-tolerant wheat will now be used by the Australian Durum Wheat Improvement Program (ADWIP) to assess its impact by incorporating this into recently developed varieties as a breeding line.

—Dr. Richard James

Although the team used molecular techniques to characterize and understand the salt-tolerant gene, the gene was introduced into the durum wheat through non-GM breeding processes. This means the novel durum wheat is not classified as transgenic, or GM, and can therefore be planted without restriction, says Munns.

The researchers are taking their work a step further and have now crossed the salt-tolerance gene into bread wheat. This is currently being assessed under field conditions.

The work was supported by the Grains Research and Development Corporation (GRDC) and Australian Research Council (ARC).

Resources

• Rana Munns, Richard A James, Bo Xu, Asmini Athman, Simon J Conn, Charlotte Jordans, Caitlin S Byrt, Ray A Hare, Stephen D Tyerman, Mark Tester, Darren Plett & Matthew Gilliham (2012) Wheat grain yield on saline soils is improved by an ancestral Na+ transporter gene. Nature Biotechnology doi: 10.1038/nbt.2120