ARS | Publication request: Microelement trafficking in plants: A Multi-compartment Journey from the Rhizosphere to Seeds

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2010
Publication Date: July 24, 2010
Citation: Grusak, M.A. 2010. Microelement trafficking in plants: A Multi-compartment Journey from the Rhizosphere to Seeds [abstract]. Plant Vascular Biology 2010. p. 37.

Technical Abstract: Essential microelements, such as Fe, Zn, Cu, Mn, and Ni, are required throughout plant growth. They are needed both to support metabolic processes in vegetative tissues and for eventual deposition in seeds to support the start of the next generation. Because these elements can be toxic in excess, their absorption from the rhizosphere and transport throughout the plant must be carefully regulated to maintain adequate, but non-toxic levels. Thus, plants have developed a cadre of membrane transporters for metal ions (and/or for metal chelates) that are coordinately utilized to traffic metal ions into the roots, on into the xylem vasculature, to the shoot apoplasmic and symplasmic spaces, and eventually to the phloem compartment for delivery to various sink tissues, such as developing seeds. In this presentation, we will introduce the various molecular mechanisms that have been identified to move metal ions across membranes and will discuss these mechanisms in the context of their role in moving metals to and throughout the long-distance vascular pathways. Specifically, we will describe how these transporters are arranged spatially and temporally to effectively move metals throughout the whole-plant continuum. We will discuss how shoot-to-root communication via the phloem pathway regulates root iron acquisition processes (and possibly the transport/uptake mechanisms of other metals). Furthermore, recent evidence for the involvement of transcription factors in the regulation of metal mobilization from source leaves to developing seeds (via the phloem pathway) will be presented. Finally, because of the multi-compartment, multi-process complexity of whole-plant metal transport, we also will focus on the missing pieces in this puzzle, thereby providing the audience with knowledge about the challenges and opportunities for further research in this area. In addition, continued research on this topic is critically needed, because a deeper understanding will allow us to effectively manipulate plant processes in ways that will enhance the micronutrient density of staple seed crops - a goal that is being targeted to combat global micronutrient deficiencies in human populations.