Plant Genetics and Physiology
Iron Homeostasis in Plants
Iron Homeostasis in Plants
Iron is one of the most important and most problematic of all the micronutrients used by living organisms. Iron is an essential cofactor for many cellular redox reactions, yet the same high reactivity that makes it so useful can cause cellular damage if iron is not carefully controlled. Add to this problem that iron is also only sparingly soluble in aqueous solution, and it is easy to see why plants have evolved multifaceted iron homeostatic mechanisms. These mechanisms include control of uptake, translocation from organ to organ and cell to cell, re-mobilization of stored iron, as well as poorly understood sensing and signaling systems by which the plant communicates its iron status between tissues. Many of the mechanisms involved in plant iron homeostasis are not well understood, and this is a major obstacle to devising approaches for biofortification of staple foods with iron. Biofortification refers to the genetic engineering of staple crops to accumulate additional bioavailable iron in edible parts; it is widely regarded as a sustainable means of improving the iron nutrition of the 2-3 billion people worldwide whose inadequate diet causes iron deficiency anemia.
My group has a strong interest in the processes by which plants move iron and other transition metals within their above ground parts. We have worked extensively on members of the Yellow Stripe Like (YSL) family of transporters are required for normal iron, zinc, and copper loading into both vegetative and reproductive tissues. Currently, we are using a combination of molecular genetic, physiological and “‘omics” approaches to understand how whole plant signaling of iron status occurs.
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. Iron-Nicotianamine Transporters Are Required for Proper Long Distance Iron Signaling . Online Early DOI: https://doi.org/10.1104/pp.17.00821. Kumar et al., 2017
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.
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.
Chu, H-H., Conte, S.S., Chan-Rodriguez, D., Vasques, K., Punshon, T., Salt, D.E., Walker, E.L. 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 cuspidate suspension culture cells. BMC Genomics 2012, 13: 148.
Roha, A. Patil, Martin E. Kolewe, Jennifer Normanly, Elsbeth L. Walker, Susan C. Roberts. 2012. Taxane biosynthetic pathway gene expression in Taxus suspension cultures with different bulk paclitaxel accumulation patterns – a molecular approach to understand variability in paclitaxel accumulation. 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.
Chu, H. H., Chiecko, J., Punshon, T., Lanzirotti, A., Lahner, B., Salt, D. E., Walker, E. L. 2010. Successful Reproduction Requires the Function of Arabidopsis YELLOW STRIPE-LIKE1 and YELLOW STRIPE-LIKE3 Metal-Nicotianamine Transporters in Both Vegetative and Reproductive Structures. Plant Physiology, 154: 197-210.
Lee, S., Chiecko, J. C., Walker, E. L., Lee, Y., Guerinot, M. L. and G. An. 2009. Disruption of OsYSL15 leads to iron inefficiency in rice plants. Plant Physiology, 150(2): 786-80.
Tharayil. N., Bhowmik, P. C., Alpert, P., Walker, E., Amarasiriwardena, D., and B. Xing. 2008. Dual purpose secondary compounds: Phytotoxin of Centaurea diffusa also facilitates nutrient uptake. New Phytologist, 181: 424-434.
Walker, E. L. and E. L. Connolly. 2008. Time to pump iron: Iron-deficiency signaling mechanisms of higher plants. Current Opinion in Plant Biology, 11(5): 530-535.
Vongpaseuth, K., Nims, E., Amand, M., Walker, E. L., and S. C. Roberts 2007. Development of a particle bombardment-mediated transient transformation system for Taxus spp. cells in culture. Biotechnology Progress, 23(5): 1180 -1185.
Waters, B. M., H. H. Chu, R. J. Didonato, L. A. Roberts, R. B. Eisley, B. Lahner, D. E. Salt, and Walker, E. L. 2006. Mutations in Arabidopsis yellow stripe-like1 and yellow stripe-like3 reveal their roles in metal ion homeostasis and loading of metal ions in seeds. Plant Physiology, 141: 1446-58.
Nims, E., C. P. Dubois, S. C. Roberts, and Walker, E. L. 2006. Expression profiling of genes involved in paclitaxel biosynthesis for targeted metabolic engineering. Metabolic Engineering, 8: 385-94.
DiDonato, R. J., Roberts, L. A., Sanderson, T., Eisley, R. B. and Walker, E. L. 2004. Arabidopsis Yellow Stripe-Like2 (YSL2): a metal-regulated gene encoding a plasma membrane transporter of nicotianamine-metal complexes. The Plant Journal, 39: 404-413.
Roberts, L. A., Pierson, A. J., Panaviene, Z., and Walker, E. L. 2004. Yellow Stripe1. Expanded Roles for the Maize Iron-Phytosiderophore Transporter," Plant Physiology, 135: 112-120.