Project Number: 6250-51000-051-20
Project Type: Specific Cooperative Agreement

Start Date: Apr 01, 2009
End Date: Mar 31, 2014

Objective:
Objective 1. Use genetic, molecular, and physiological approaches to define the role of specific genes and gene products in the acquisition and whole-organism partitioning of minerals (iron, zinc, calcium, and magnesium) and other factors that inhibit or promote absorption of these minerals in plant foods. Sub-objective 1.A. Identify quantitative trait loci (QTLs) associated with elevated seed or leaf mineral concentrations or seed biomass accumulation. Sub-objective 1.B. Identify rate-limiting and/or novel genes that contribute to tissue Fe, Zn, Ca, and Mg concentrations or seed biomass accumulation. Sub-objective 1.C. Assess the functional role of newly identified gene products in whole-plant nutrition and nutrient partitioning. Sub-objective 1.D. Measure the effects of modulating cation transporter functions on plant Ca, Mg, Fe and Zn content. Sub-objective 1.E. Measure the impact of altered transport function in agriculturally important crops. Sub-objective 1.F. Identify and isolate genes that are involved in calcium oxalate crystal formation in selected mutants. Sub-objective 1.G. Assess the role of the identified genes in calcium oxalate crystal formation. Objective 2. Conduct animal and human feeding studies to determine mineral bioavailability of the nutritionally enhanced crops. Sub-objective 2.A. Use novel transgenic plants to dissect the relationship between mineral partitioning and nutrient absorption in mice feeding studies. Sub-objective 2.B. If the rodent studies demonstrate proof of concept, initiate pilot feeding studies using young adults. Objective 3. Develop new, cost-effective methods for the intrinsic labeling of plant foods for use in nutrient bioavailability studies.

Approach:
The long-term objective of this project is to contribute to the development of nutritionally enhanced plant foods and to develop tools for testing nutrient bioavailability. We have chosen to work initially with plants that are tractable molecular genetic systems (Arabidopsis, Medicago, and soybean) where we can perform gene discovery quickly. We then translate these findings into agriculturally important crops that can be easily transformed and for which established protocols are in place for measuring nutrient absorption in both mice and humans. Specifically, we will work to identify and characterize genes and gene products that are involved in mineral transport throughout the plant, focusing both on whole organ accumulation and subcellular partitioning of minerals. We also will identify and characterize the molecular processes associated with calcium oxalate formation in plants. We envision this work to eventually have relevance to mineral nutrition improvement (e.g., calcium, magnesium, iron, and zinc) in several agronomic crops. In addition, we will develop new, cost-effective methods for the intrinsic labeling of plant foods, using stable isotopes, in order to facilitate nutrient bioavailability studies in humans. These efforts will expand our capabilities for assessing the absorption and metabolism of various plant-derived minerals and phytochemicals. They also will facilitate the generation of new bioavailability data for various nutrients, which will allow informed decisions when policymakers establish future dietary recommendations for humans.