Key to salt-tolerant wheat uncovered

In a recent set of papers published in the journal Plant Physiology , researchers have described how two genes known as Nax1 and Nax2 - work by excluding salt from different parts of the plant: one from the roots, the other from the leaves. The discovery of the two genes, which are the subject of international patents, could be significant. Over six per cent of the worlds arable land is affected by salinity. Salt tolerant crops could therefore provide farmers with income for remediation, as well as helping to stabilise soil from wind and water erosion. And with increasing pressure on food commodity supplies from the growing biofuels market, making use of all available land will become an increasingly important consideration. The two genes originally came from a wheat ancestor, Triticum monococcum, said research team leader, CSIRO (Commonwealth Scientific and Industrial Research Organisation) plant industrys Dr Rana Munns. They were unwittingly crossed into a durum wheat line about 35 years ago and are normally not present in any modern wheat. The project began when the CSIRO team used a highly accurate selection method based on their understanding of how plants tolerate salt to identify wheat varieties that could cope with higher salinity. They were particularly interested in the premium-priced durum wheat, which is much more salt-sensitive than bread wheat. We screened a hundred durum wheats from the Australian Winter Cereals Collection at Tamworth, which contains tens of thousands of wheat types, said Munns. Highlighting the fact that the science of plant breeding sometimes relies on an element of good fortune, we were lucky to find the durum variety with the ancient genes straight away, otherwise we might have been looking for years. The team used their knowledge of the two genes to construct molecular markers, which are now in use in CSIROs wheat breeding programme. A durum wheat variety as salt-tolerant as bread wheat is in advanced field trials, and could be commercially available in three years. Even better durum wheats are in development and the program has been expanded to include bread wheat. Bread wheat is quite tolerant to salt, but we think it too can be improved. Our aim is to eventually produce wheats able, like barley, to grow in highly saline soils, said Munns. The breakthrough is the latest in a number of developments designed to better safeguard the supply of commodities. The Consultative Group on International Agricultural Research (CGIAR), which is working to reduce developing countries vulnerability to climate change caused by global warming, recently highlighted the work being done on the development of heat-resistant cereals. Researchers are also looking to boost rice yields from a shrinking land base by reconfiguring the plants photosynthetic engine so that it more efficiently converts solar power and atmospheric carbon into grain. As a result of rising temperatures, the climatic conditions best suited to wheat growing will shift away from the tropics where most of the worlds poorest countries are situated toward the poles and to higher elevations. According to a recent study, North American wheat growers will be able to farm new lands as far as 65 degrees north, 10 degrees beyond their current planting limit.

Key to salt-tolerant wheat uncovered

A major advance in breeding new salt-tolerant varieties of wheat could have important implications for future supplies.

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