Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 7, 2006
Publication Date: July 7, 2006
Citation: Grusak, M.A. 2006. Plant sources of dietary iron: Diversity in tissue iron concentration. In: Proceedings of the Thirteenth International Symposium on Iron Nutrition and Interactions in Plants, July 3-7, 2006, Montpellier, France. 2006. Abstract p. 56. Technical Abstract: Iron is an essential mineral for all organisms, including humans and other animals. Iron must be obtained through dietary sources, and plant food products are an important provider of this micronutrient. Because all plants contain iron, humans consume this nutrient in all vegetable, grain, and fruit products. Additionally, all animal-derived foods that are consumed by man also contain iron that previously was packaged in a plant tissue (e.g., forage). Some plant foods are better sources of iron than others, being higher in iron concentration and/or containing food components that enhance iron bioavailability. Interestingly, this diversity in composition occurs not only between plant species, but also within genotypes of a single species. Understanding the basis for this diversity is an important goal that we and others believe will enable the development of iron-enriched cultivars for human consumption. This improvement is critical, because diet-dependent iron deficiency is widespread amongst human populations throughout the world. In this talk, I will provide an overview of the range of iron concentrations found in plant foods, with data derived from several germplasm evaluations that we and others have conducted in recent years. The identification of high-iron concentration and low-iron concentration genotypes has provided valuable tools to study the underlying bases for these genotypic and species differences. I will review how root acquisition processes, xylem delivery to transpiring tissues, and phloem remobilization to developing sinks are functionally integrated to ensure an adequate and appropriate distribution of iron within the whole-plant network. In support of this concept, the results of several iron partitioning analyses will be presented, which demonstrate the critical need for iron uptake throughout a plant's life cycle. Root uptake is important not only for elevated iron accretion in leaves and other transpiring organs, but often merely to maintain a continual pool of iron in these tissues for subsequent phloem delivery to sink regions. I will use these results to present candidate molecular mechanisms and physiological processes that will need to be targeted if we are to effectively improve the iron concentration within plant foods. It will be noted that these candidate processes will differ across species. Critical areas that require additional investigation will also be discussed. The work and analyses to be presented were supported in part by funds from USDA-ARS under Agreement No. 58-6250-6-001 and from the Harvest Plus Project under Agreement No. 58-6250-4-F029.