Researchers investigate breeding a “hardier, more nutritious wheat”

16 Apr 2020 --- Some new crop varieties are bred to be more nutritious. Others are more resilient, bred to tolerate harsh environmental conditions. In a recent study from the American Society of Agronomy, researchers report on a variety of wheat that combines enhanced nutrition with increased resilience. During the study, the researchers also tested a breeding method that could reduce costs and save time compared to traditional methods.

The newly developed wheat variety contains higher levels of a naturally occurring carbohydrate, called fructans. “Wheat with increased fructan levels can be more climate-resilient in certain situations,” says Lynn Veenstra, a researcher at Cornell University, New York, US. “These situations include high salinity or cold temperatures.”

A source of soluble fiber
Fructans are long chains of the sugar fructose. Unlike the fructose present in foods, such as high-fructose corn syrup, fructans cannot be digested by humans. This makes fructans a good source of soluble fiber. Previous research has shown that consuming foods with higher fructan levels could also promote healthy gut bacteria.

In the US, a large portion of daily fructan intake comes from wheat products, such as bread. That makes developing high-fructan wheat important, the researchers note. Yet there is another advantage to using high-fructan wheat. “We wouldn't have to supplement wheat products with fructans or fiber from other sources,” explains Veenstra. “This wheat would already contain higher levels of fructans.”

However, breeding high-fructan wheat can be time-consuming and expensive. “The development of nutritionally improved wheat varieties often requires extensive resources,” adds Veenstra.

Typically, a process called phenotyping takes the most time. Phenotyping is the measurement of crop characteristics – like fructan levels or yield.

Phenotyping allows plant breeders to compare new and existing varieties of crops. For example, they can test if newer varieties have higher or lower fructan levels than existing crops. At the same time, they need to make sure other crop features – like yield or disease resistance – are not reduced.

Click to EnlargeA relatively new breeding method can expedite the development of new crop varieties, according to the researchers.New breeding methods
A relatively new breeding method can expedite the development of new crop varieties. Veenstra and her colleagues tested variations of this method, called genomic selection.

Genomic selection uses a relatively small “training” set of individual plants. Researchers combine phenotyping and genetic data from this training set of plants and then they use these data to train a statistical model. Once trained, the statistical model can predict plant characteristics – like fructan levels – based solely on genetics.

According to Veenstra, this allows crop breeding without needing to collect data on observed characteristics. 

Genomic selection saves time and resources in two ways; firstly, the training set of plants is relatively small. That allows phenotyping to be concluded quickly. Secondly, genetic testing can often be much quicker than measuring crop characteristics.

Ultimately, genomic selection can allow breeders to save both cost and time during the breeding process, the researchers highlight. 

Limitations of genomic selection
Previously, FoodIngredientsFirst reported that UK researchers developed a wheat genetic modification system. Last November, researchers at UK-based John Innes Centre (JIC) developed an open-source reproducible Agrobacterium-mediated transformation system for the spring wheat cultivar “Fielder” (Triticum aestivum L.). While transformation efficiency for wheat has languished around 5 percent for many years despite its global importance, the new system can yield efficiencies of up to 25 percent of those generally achieved using comparable systems.

There are some caveats to using genomic selection, though, the researchers from Cornell University highlight. Inbreeding can happen, for instance, which can reduce crop diversity. Reduced diversity can make crops susceptible to diseases.

The researchers tested two different modes of genomic selection. They found that one method led to wheat with higher fructans while maintaining genomic diversity.

“This is the most important finding of this study,” Veenstra claims. “Genomic selection can be used for nutritional breeding,” she affirms. 

Researchers still need to know more about the fructans in the new wheat variety. “We also want to determine how stable these fructans are during food processing,” she adds. For example, yeast degrades different fructans at different rates. That would impact how much fructan ends up in a loaf of bread.

“I believe both wheat growers and consumers stand to benefit from high-fructan wheat,” Veenstra continues. “For wheat growers, high-fructan varieties have the potential to withstand climatic stress. For consumers, high-fructan wheat products may have positive impacts on gut health,” she concludes. 

Edited by Elizabeth Green

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