Natural soil fungi symbiosis shown to boost micronutrients in wheat

Inoculating eight widely grown Australian bread wheat varieties with a commercially available arbuscular mycorrhizal — a symbiosis between plants and members of an ancient phylum of fungi — fungus product caused the plants to grow more grain and accumulate greater amounts of nutrients, according to recent research at the University of Adelaide, Australia.

Moreover, the symbiosis allows for more bioavailable zinc and iron in the plants.

“Our research shows inoculating agricultural soils with mycorrhizal fungi could be a promising strategy for producing wheat grain with higher micronutrient bioavailability, without compromising agronomic practices, such as the use of phosphorus as a fertilizer, or yield targets,” says University of Adelaide Ph.D. student and lead author, Thi Diem Nguyen.

The researchers believe enhancing zinc and iron bioavailability in wheat grains can help to combat human nutritional deficiencies experienced globally. The note that bread wheat is the world’s second largest food crop, second only to rice. Wheat products, such as bread, contribute up to 17% of the dietary intake of zinc and iron.

Effects on bioavailability

Research at the University of Adelaide shows that adding a specific fungus to eight common Australian bread wheat varieties increases their grain yield and nutrient content.According to the study published in Plants, People, Plant, the fungus caused the wheat to take up more phosphorus from the soil. However, this did not lead to the grain accumulating additional phytic acid — also called antinutrients — that can impact micronutrients’ bioavailability in the gut.

“We found that fungal inoculation did not affect grain phytate content under low soil phosphorus conditions, and even reduced phytate levels in some varieties under high soil phosphorus, leading to greater estimated bioavailability of zinc and iron in grains in the fungus-inoculated plants,” says Nguyen.

“Importantly, this suggests that for bread wheat, there is no trade-off between grain yield and nutritional quality of inoculated plants when phosphorus fertilizer is applied.”

Targeting micronutrient deficiencies

Project leader Dr. Stephanie Watts-Fawkes underscores that micronutrient deficiencies, especially of zinc and iron, are widespread among populations in low- and middle-income countries. 

“Zinc deficiencies affect approximately 30% of the global population, and 60% experience iron deficiencies, with sometimes dire health consequences,” she details. “Human zinc deficiency affects normal development during pregnancy, childhood, and adolescence, skin and hair, and leads to diarrhea and diseases.”

“The most common outcome of human iron deficiency is iron-deficiency anemia, which is associated with impaired immune function and cognitive development, and causes higher mortality of mothers and children at birth.”

In other crop science, researchers in a previous paper found that rising global temperatures and carbon dioxide reduce the vitamins, minerals, and overall nutritional quality and content of leafy vegetables. They warn that climate-induced changes may accelerate obesity, type 2 diabetes, and vitamin deficiency rates among humans and animals.