Web site: Ivan Baxter, USDA-ARS Office phone:
Interest includes the understanding how plants regulate the mobilization, uptake, translocation, and storage of elements in different environments. We are focusing our efforts on the seeds of corn and soybeans. The seeds are important not only as the component of the plant that gets used for food, but also as a summary tissue of many physiological processes that are important for plant growth. We also study model systems to understand basic processes and apply this knowledge to the crop plants.
Understanding how plants regulate element composition of tissues is critical for agriculture, the environment, and human health. Sustainably meeting the increasing food and biofuel demands of the planet will require growing crops with fewer inputs such as the primary macronutrients phosphorus(P) and potassium(K). P in fertilizer is non-renewable, too expensive for subsistence farmers, and inefficiently utilized by crops, leading to runoff and severe downstream ecological consequences. Plants comprise the major portion of the human diet, and improving their elemental nutrient content can greatly affect human health. However, efforts directed at a single element can have unforeseen deleterious effects. For example, limiting iron (Fe) or P can lead to increased accumulation of the toxic elements cadmium (Cd) and arsenic (As).
The focus of our attempts to study this question is ionomics. We analyze the elemental content of 500-1000 samples per week using ICP-MS. We use this high throughput to study structured genetic populations grown in different environments. When we combine this data with cutting-edge statistical and bioinformatics methodologies, we are able to identify genes and Gene X Environment interactions which are important for elemental accumulation in plants.
- Baxter, I., Brazelton, J.N., Yu, D., Huang, Y.S., Lahner, B., Yakubova, E., Li, Y., Bergelson, J., Borevitz, J.O., Nordborg, M., Vitek, O., and Salt, D.E. (2010). A Coastal Cline in Sodium Accumulation in Arabidopsis thaliana; Is Driven by Natural Variation of the Sodium Transporter AtHKT1;1. PLoS Genet 6, e1001193.
- Atwell, S., Huang, Y.S., Vilhjalmsson, B.J., Willems, G., Horton, M., Li, Y., Meng, D., Platt, A., Tarone, A.M., Hu, T.T., Jiang, R., Muliyati, N.W., Zhang, X., Amer, M.A., Baxter, I., Brachi, B., Chory, J., Dean, C., Debieu, M., de Meaux, J., Ecker, J.R., Faure, N., Kniskern, J.M., Jones, J.D., Michael, T., Nemri, A., Roux, F., Salt, D.E., Tang, C., Todesco, M., Traw, M.B., Weigel, D., Marjoram, P., Borevitz, J.O., Bergelson, J., and Nordborg, M. (2010). Genome-wide association study of 107 phenotypes in Arabidopsis thaliana inbred lines. Nature.
- Baxter, I. (2010). Ionomics: The functional genomics of elements. Brief Funct Genomic Proteomic 9, 149-156.
- Buescher, E., Achberger, T., Amusan, I., Giannini, A., Ochsenfeld, C., Rus, A., Lahner, B., Hoekenga, O., Yakubova, E., Harper, J.F., Guerinot, M.L., Zhang, M., Salt, D.E., and Baxter, I.R. (2010). Natural genetic variation in selected populations of Arabidopsis thaliana is associated with ionomic differences. PLoS One 5, e11081.
- (2010). Genome sequencing and analysis of the model grass Brachypodium distachyon. Nature 463, 763-768.
- Morrissey, J., Baxter, I.R., Lee, J., Li, L., Lahner, B., Grotz, N., Kaplan, J., Salt, D.E., and Guerinot, M.L. (2009). The ferroportin metal efflux proteins function in iron and cobalt homeostasis in Arabidopsis. Plant Cell 21, 3326-3338.
- Danku, J., Gumaelius, L., Baxter, I., and Salt, D.E. (2009). A high-throughput method for Saccharomyces cerevisiae (yeast) ionomics. Journal of Analytical Atomic Spectrometry 24, 103-107.
- Baxter, I., Vitek, O., Guerinot, M.L., and Salt, D.E. (2009). Reply to Evens and Niedz: Multivariate ionomics models are robustly validated. Proc Natl Acad Sci U S A 106, E7E7.
- Baxter, I., Hosmani, P.S., Rus, A., Lahner, B., Borevitz, J.O., Muthukumar, B., Mickelbart, M.V., Schreiber, L., Franke, R.B., and Salt, D.E. (2009). Root suberin forms an extracellular barrier that affects water relations and mineral nutrition in Arabidopsis. PLoS Genet 5, e1000492.
- Baxter, I. (2009). Ionomics: studying the social network of mineral nutrients. Curr Opin Plant Biol 12, 381-386.