Enhancing mineral content in plant food products.

Plant foods can serve as dietary sources of all essential minerals required by humans. Unfortunately, mineral concentrations are low in some plants, especially many staple food crops; thus, efforts are underway to increase the mineral content of these foods as a means to ensure adequate attainment of dietary minerals in all individuals. While these efforts have included classical breeding approaches in the past, it is clear that future progress can be made by utilizing the tools of biotechnology to effect directed changes in plant mineral status. Reviewed are the short- and long-distance mineral transport mechanisms responsible for the root acquisition and whole-plant partitioning of mineral ions in crop plants. This background is used to discuss different transgenic strategies with the potential to enhance mineral content in vegetative and/or reproductive tissues. Due to various constraints imposed by plant transport systems on whole-plant mineral movement, it is argued that modifications designed to increase the supply of minerals to edible organs should have the highest chance for success. Examples of previous efforts to manipulate plant mineral nutrition through the introduction of novel transgenes are presented to demonstrate the utility of these approaches.