Elsbeth L. Walker
Elsbeth Walker’s main area of research focuses on understanding the fundamental mechanisms underlying iron homeostasis in plants, which can set the foundation for increasing available iron in food crops. Her work on this subject began with the identification of Yellow Stripe1 (YS1), which encodes the iron-phytosiderophore transporter that is responsible for primary iron uptake in grass species. Subsequently, her group investigated the related family of proteins, YELLOW STRIPE1-LIKEs (YSLs), and demonstrated their involvement in the long distance movement of metals in plants. She is keenly interested in uncovering additional features of both the iron uptake, and long distance iron movement pathways.
Prior work on the regulation and localization of Arabidopsis iron transporters, OPT3, YSL1 and YSL3 has indicated that they have opposite but indispensible roles in controlling shoot-to-root signaling of iron status. A working hypothesis that explains current observations is that OPT3 and YSL1/YSL3 together modulate phloem companion cell Fe status, and that low concentrations of Fe in the companion cells results in the production of a phloem mobile signal that initiates iron deficiency regulated gene expression in roots. In this project, a combination of transporter activity studies, protein localization, and highly accurate determination of the metal distribution in veins will test this hypothesis. The project scientists have established the presence of a phloem-mobile inductive RNA signal that is capable of inducing iron deficiency associated gene expression in excised roots. Because a simple assay system for the phloem mobile signal has been developed, profiling experiments coupled with downstream genetic analyses will be used to identify the phloem mobile signal produced in iron deficient leaves that regulates root gene expression.
- Postdoctoral Yale University,1990-1993
- Ph.D Rockfeller University, 1990