Scientists develop new drought resistant grain

25 March 20224 min reading

Australian scientists have identified a novel combination of genetics that may help wheat survive in hot and dry conditions, thereby increasing yields and assisting farmers to adapt to climate change-induced heat and drought stress.

Wheat is the third-largest grain crop in the world, supplying about 20 percent of the total calories and protein in the human diet worldwide, notes the research by CSIRO, Australia’s national science agency, published in Nature Climate Change on March 7.

By-products of the milling process, such as wheat bran, are most commonly fed to horses. Wheat bran is the hard outer coating of the kernel, and is 12 percent digestible protein. It is highly palatable and is frequently used to add to increase phosphorus content and bulk to a diet, such as in a mash. Wheat middlings are fine particles of the wheat kernel obtained during the milling process. If wheat middlings are fed to horses, they must be mixed with a bulky feed.

The Australian researchers have identified three novel alternative dwarfing genes that enable wheat seeds to draw moisture stored twice as deep from the soil than current varieties.

Greg Rebetzke, co-author of the study and chief research scientist at CSIRO Agriculture and Food, said this meant that seeds could be sown earlier and deeper, up to 120mm, while keeping the plants short and allowing for very long coleoptile, which is the shoot that grows from the seed to the soil surface. A coleoptile is like a drinking straw that can push through dry and hard soil, allowing the germinating wheat leaves to emerge above the ground,” Rebetzke explains.

In many parts of Argentina, Australia, Bangladesh, Canada, China, India, Mexico, Pakistan, and the US as well as in the Middle East and North Africa, wheat crops rely only on rainfall.

“Long coleoptiles in future wheat varieties can help maintain or increase the yield in hotter and drier environments and provide growers assurance that they can sow deep and will reap a harvest,” Rebetzke says. “Even in irrigated fields, as global warming pushes soil temperatures to rise, we will need a long coleoptile for a short germination and emergence of the crop.”

The study estimates that new wheat varieties with longer coleoptiles, coupled with deep sowing, can increase yields by 18 to 20 percent under historical climate (1901–2020), with benefits projected under future global warming.

Zhigan Zhao, lead author and crop modeller at CSIRO, said that crop modelling enabled the team to integrate field data and understanding of physiology and genetics to predict the yield of the novel wheat varieties with long coleoptile across environments. “This has made it possible to put a dollar value on the benefits of the long coleoptile wheat,” he says. The study estimates that wheat varieties with longer coleoptiles could increase farmers’ profits in Australia by $US1.6 billion annually on average.

Researchers say learnings from this study could be translated to other crops – rice, barley, oats and rapeseed – to improve the resilience and reliability of farming in future climates.

“Breeding companies are investigating the use of novel genes to breed new wheat varieties with longer coleoptiles in Australia and through collaborators in the US and parts of Europe,” Rebetzke says.

Devinder Sharma, a food policy analyst and an agricultural expert based in India, said the availability of soil moisture at the surface, and also at the root zone, would be critical for future food production. “The temperature rise, we are already seeing, is increasingly leading to dryness of the soil surface. This will only worsen with climate change, thereby posing a serious problem for global food production.“Developing a new wheat variety, incorporating the novel GAS (gibberellic-acid-sensitive) dwarfing gene, that takes advantage of soil moisture at the sub-surface and enables the plant to germinate when sown at a depth that is twice the normal practice has potential,” Sharma says.“But whether the new genotypes can perform equally well in different soil types, and with temperature and rainfall variations, is something to be tried out.”

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