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Elsbeth L. Walker

Professor

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.

Current Research
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.

Academic Background

  • Postdoctoral Yale University,1990-1993
  • Ph.D Rockfeller University, 1990
Chan Rodriguez, D. and E. L. Walker (2018) Analysis of yellow striped mutants of Zea mays reveals novel loci contributing to iron deficiency chlorosis. Frontiers in Plant Science
Kumar, R. K., Chu, H-H., Abundis, C. A., Vasques, K., Chan-Rodriguez, D., Chia, J-C, Huang, R., Vatamaniuk, O. K., and E. L. Walker (2017) The Iron-Nicotianamine Transporters, Yellow Stripe1-Like1 and 3 Regulate Long Distance Shoot to Root Signaling of Iron Deficiency in Arabidopsis. Plant Physiology 175:1254. DOI: https://doi.org/10.1104/pp.17.00821
Lenka, S.K., Nims, N. E., Vongpaseuth, K., Boshar, R. A., Roberts, S. C. and E. L. Walker (2015) Jasmonate-responsive expression of paclitaxel biosynthesis genes in Taxus cuspidata cultured cells is negatively regulated by the bHLH transcription factors TcJAMYC1, TcJAMYC2 and TcJAMYC4. Frontiers in Plant Science 6:115. doi: 10.3389/fpls.2015.00115.
Patil, R.A., Lenka, S.K., Normanly, J., Walker, E.L., and S.C. Roberts (2014) Methyl jasmonate represses growth and affects cell cycle progression in cultured Taxus cells. Plant Cell Reports 33: 1479-1492 DOI: 10.1007/s00299-014-1632-5.
Conte S. S., Chu H. H., Rodriguez D. C., Punshon T., Vasques K. A., Salt D. E., and E. L. Walker (2013) Arabidopsis thaliana Yellow Stripe1-Like4 and Yellow Stripe1-Like6 localize to internal cellular membranes and are involved in metal ion homeostasis. Frontiers in Plant Science 4:283.
Lenka, S. K., Boutaoui, N., Paulose, B., Vongpaseuth, K., Normanly, J., Roberts, S. C. and E. L. Walker (2012) Identification and expression analysis of methyl jasmonate responsive ESTs in paclitaxel producing Taxus cuspidata suspension culture cells. BMC Genomics 13:148.
Rohan A. Patil, Martin E. Kolewe, Jennifer Normanly, Elsbeth L. Walker, Susan C. Roberts (2012) Contribution of taxane biosynthetic pathway gene expression to observed variability in paclitaxel accumulation in Taxus suspension cultures. Biotechnology Journal 7: 418–427.
Yordem, B. K., Conte, S. S., Ma, J. F., Yokosho, K., Vasques, K. A., Gopalsamy, S. N. and Walker, E. L. (2011) Brachypodium distachyon as a new model system for understanding iron homeostasis in grasses: phylogenetic and expression analysis of Yellow Stripe-Like (YSL) transporters. Annals of Botany, 108(5): 821-835.
Walker E. L., Waters B. M. (2011) The role of transition metal homeostasis in plant seed development. Current Opinion in Plant Biology 14(3):318-24.
Conte, S. S. and Walker. E. L. (2011) Transporters Contributing to Iron Trafficking in Plants Molecular Plant 4(3):464-76.
 
Contact Info

Biology
374 Morrill IVS
639 N Pleasant Street
Amherst, MA 01003-9292

(413) 545-0861
ewalker@bio.umass.edu
www.bio.umass.edu/biology/ewalker