Salt-tolerant wheat a breakthrough for better yields
Australian scientists have successfully carried out field trials of a salt-tolerant durum wheat, boosting grain yield by 25 per cent in salty soils.
Durum is one of the most widely grown cereals in the world, but in saline soils it is vulnerable to salt build-up in the leaves, which can hinder growth and reduce yields, threatening food security.
The researchers at the University of Adelaide and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) had previously found that Triticum monococcum — an ancestral cousin of modern wheat — has a genetic ability to avoid sodium build-up. Using conventional breeding techniques, the team introduced this trait into commercial durum wheat.
They have now described how the salt tolerance gene functions, and this work, together with their field study results, appeared in this week's Nature Biotechnology (11 March).
"The gene encodes a protein which removes the sodium [salt] from the cells lining the xylem, which are the 'pipes' [the] plants use to move water from their roots to their leaves," contributing author, Matthew Gilliham, from the University of Adelaide's Waite Research Institute, told SciDev.Net.
"The study proves a concept that salinity tolerance can be improved in cereals and opens up the doors for conventional breeding to transfer this gene to a whole host of wheat and plant varieties," said Gillham.
He said the seeds should be commercially available within five years, and that the trait is currently being introduced and tested in bread wheat, with promising results.
Soil salinity affects over 20 per cent of the world's agricultural soils and is a serious challenge, particularly for irrigated agriculture and in regions of the world where natural salinity levels are high — including parts of the Middle East and North Africa. In the United States — the world's largest exporter of wheat — "production losses due to salinity are worth over US$12 billion," Gilliham said.
Using conventional breeding techniques rather than genetic modification (GM) could make the resulting seeds cheaper and more acceptable to farmers, according to Ephraim Nkonya, senior research fellow at the International Food Policy Research Institute (IFPRI).
"A conventionally-bred crop is more likely to be adopted in the developing world. The beauty of [conventional] breeding is that the cost of seeds is not [too] much," Nkonya said, adding that there would also be fewer planting restrictions for farmers to negotiate.
However, a spokesman for the International Maize and Wheat Improvement Centre (CIMMYT) expressed concern that breeding for salt tolerance could encourage farmers to continue poor irrigation practices.
Nature Biotechnology (2012) doi:10.1038/nbt.2120