Zinc Dynamics in Soil, Transport and Assimilation in Plants

The global population is projected to increase by 25% by 2050, adding approximately 2 billion people, significantly intensifying the demand for food. Ensuring food production and accessibility enriched with essential minerals is crucial to addressing malnutrition. Currently, 2 billion people worldwide suffer from micronutrient deficiencies, with zinc (Zn) deficiency being a critical concern for crops, humans, and animals. Alarmingly, 50% of cultivated soils used for cereal production are Zn-deficient, exacerbating the problem. In plants, Zn is indispensable, contributing to enzyme activation, auxin synthesis, protein production, and maintaining membrane integrity. Natural and anthropogenic sources of Zn include surface water, soil, rocks, industrial activities, agricultural practices, fertilizers, and pesticides. Despite these sources, Zn deficiency remains a widespread issue because only a small fraction of the total Zn in soils is available to plants. This limitation arises from various soil transformation processes, such as sorption by clays, hydrous oxides, and organic matter, which reduce Zn bioavailability. Plants primarily absorb Zn in its divalent cation form (Zn²⁺) from the soil solution. Specialized Zn transporters play a crucial role in facilitating the diffusion of Zn across cell membranes, driven by membrane potential. Once inside, Zn is assimilated into various plant tissues, supporting critical physiological and biochemical processes. However, the limited availability of Zn in soils restricts plant growth and nutrition, ultimately impacting food quality and human health. Addressing Zn deficiency requires targeted strategies, including improving Zn availability in soils and adopting sustainable agricultural practices. Enhanced understanding of Zn dynamics in soil-plant systems can help optimize Zn uptake, contributing to improved crop productivity and addressing the global challenge of malnutrition.