Genetic biofortification of wheat with zinc: Opportunities to fine‐tune zinc uptake, transport and grain loading

Abstract

Zinc (Zn) is an important micronutrient in the human body, and health complications associated with insufficient dietary intake of Zn can be overcome by increasing the bioavailable concentrations in edible parts of crops (biofortification). Wheat (Triticum aestivum L) is the most consumed cereal crop in the world; therefore, it is an excellent target for Zn biofortification programs. Knowledge of the physiological and molecular processes that regulate Zn concentration in the wheat grain is restricted, inhibiting the success of genetic Zn biofortification programs. This review helps break this nexus by advancing understanding of those processes, including speciation regulated uptake, root to shoot transport, remobilisation, grain loading and distribution of Zn in wheat grain. Furthermore, new insights to genetic Zn biofortification of wheat are discussed, and where data are limited, we draw upon information for other cereals and Fe distribution. We identify the loading and distribution of Zn in grain as major bottlenecks for biofortification, recognising anatomical barriers in the vascular region at the base of the grain, and physiological and molecular restrictions localised in the crease region as major limitations. Movement of Zn from the endosperm cavity into the modified aleurone, aleurone and then to the endosperm is mainly regulated by ZIP and YSL transporters. Zn complexation with phytic acid in the aleurone limits Zn mobility into the endosperm. These insights, together with synchrotron‐X‐ray‐fluorescence microscopy, support the hypothesis that a focus on the mechanisms of Zn loading into the grain will provide new opportunities for Zn biofortification of wheat.

Improving Dietary Zinc Bioavailability Using New Food Fortification Approaches: A Promising Tool to Boost Immunity in the Light of COVID-19

“…The Zn content in plants may be easily and cheaply increased using this approach. Genetic biofortification, though time consuming, is also an effective method for lowering the risk of micronutrient deficiencies [ 68 ]. On other hand, the technological processing of food raw materials results in a decrease in the content of nutrients, which leads to an insufficient intake of minerals and vitamins.…”

Zinc-Fortified Rice: Approach to Improve Dietary Zinc Consumption and Effect on Human Health

“…A more appropriate long-term robust strategy is required, which can increase bioavailable Zn concentration in staple crops, improve easy accessibility, and control toxicity effects. 61 Thus, there is a need for genetic Zn biofortification. To successfully increase genetic gain for Zn concentration in the rice grain, it is important to gain a better understanding of genetic and environmental interactions that regulate Zn homeostasis in rice.…”

Functions and strategies for enhancing zinc availability in plants for sustainable agriculture

“…The H + ATPase vigorously pumps H + ions out of the cell, as a consequence of ATP hydrolysis. In the rhizosphere, H + production enhances cation absorption by decreasing soil pH and hyperpolarizing the root plasma membrane (Kamaral et al, 2022). To transfer from one place to another inside a cell, divalent cations like Zn must be transported by particular transporter proteins (Eide, 2006;Lu et al, 2013;Gupta et al, 2016).…”

“…Long-distance translocation (root to shoot) of Zn is mostly accomplished in the xylem via the transpiration stream (Page and Feller, 2015), as shown in Figure 2. Meanwhile, it requires energy and a number of active transporters are engaged in the transport and unloading of Zn in the xylem (Kamaral et al, 2022). Zn can flow as a free cation or as a compound in the xylem, although the acidic pH (5.5) of xylem sap promotes transportation as a neutral Zn 2+ ion (Alves et al, 2004).…”