Arbuscular mycorrhizal fungal inoculation and soil zinc fertilisation affect the productivity and the bioavailability of zinc and iron in durum wheat
There is a growing recognition of the role of arbuscular mycorrhizal fungi (AMF) in food security, specifically the potential for AMF to enhance the yield and mineral nutrition—including phosphorus, zinc (Zn), and iron (Fe)—of food crops. However, the bioavailability of Zn and Fe for humans in the grain of cereal crops can be overestimated by failing to consider the abundance of phytic acid (PA). This is because PA can chelate the micronutrients, making them difficult to absorb. In order to understand the effect of an AM fungus and soil Zn concentration on the productivity and nutritional quality of food parts, this study examined the growth and nutritional responses of durum wheat, with and without inoculation with Rhizophagus irregularis, at five soil Zn concentrations. Growth and nutrient responses of the plants to soil Zn amendment was stronger than responses to AMF. However, the protective effect of AMF under soil Zn toxicity conditions was observed as reduced Zn concentration in the mycorrhizal durum wheat grain at Zn50. Here, AMF inoculation increased the concentration of PA in durum wheat grain but had no effect on the concentration of Zn and Fe; this consequently reduced the predicted bioavailability of grain Zn and Fe, which could lead to a decrease in nutritional quality of the grain. This research suggests that in soil with low (available) phosphorus and Zn concentrations, AMF may reduce the food quality of durum wheat because of an increase in PA concentration, and thus, a decrease in the bioavailability of Zn and Fe.
KeywordsRhizophagus irregularis Biofortification Plant nutrition Micronutrient bioavailability Phytic acid
The authors would like to thank Professor Mike McLaughlin and Ms. Bogumila Tomczak for access to the ICP-AES, and Ms. Andrea Ramirez Sepulveda and Ms. Cuc Tran for technical assistance. We also thank the anonymous reviewers and the editor of this manuscript for valuable feedback.
BTTT acknowledges the Vied-Adelaide University joint scholarship. SJWW acknowledges the University of Adelaide Ramsay Fellowship and the Australian Research Council Centre of Excellence in Plant Energy Biology for support (Grant number CE140100008).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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