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Elena D. Shpak Assistant Professor, Department of Biochemistry, Cellular & Molecular Biology MS: Plant physiology - Moscow State University, Russia PhD: Biochemistry - Ohio University, Athens F-431 Walters Life Sciences Knoxville, TN 37996 Phone: (865) 974-8383 eshpak@utk.edu

Keywords:
signal transduction, receptor kinases, organ size regulation, plant growth and development, Arabidopsis

Description of Research:
The focus of my research is plant growth and development using Arabidopsis as a model system. Specifically we are studying the genetic regulation of organism size. California's coastal redwood tree can grow to a height of 350 feet, an equivalent of a 35-story skyscraper. At the same time, aquatic watermeal plants (genus Wolffia) are so small that they resemble specks of cornmeal floating on the water. Why are some plants so large, while others are so small? Plant organs grow from organ primordia that are formed by the continuous activity of apical meristems. While the meristem determines the size, number and identity of primordia, later processes in the primordia define the final shape and size of organs. We are using a simple plant organ – pedicel - to understand mechanisms regulating tissues grow. A pedicel is a small stalk that connects the flower/fruit to the stem. Using histological approach we study chronologically cell proliferation and elongation patterns in known and new Arabidopsis mutants and use these data to build a computer model of the pedicel growth.

We are also studying the ERECTA-mediated signaling, one of the pathways that determines size and shape of aboveground plant organs. ERECTA is a receptor-like kinase (RLK) with an extracellular leucine-rich repeat domain, a single transmembrane domain, and a cytoplasmic Ser/Thr kinase domain. Two functional paralogs of ERECTA, ERL1 and ERL2, are redundant with ERECTA in part of the signaling pathway. Loss of the entire ERECTA family in Arabidopsis leads to dwarfism, a decrease in lateral organ size, abnormal flower development and changes in stomatal patterning. The ERECTA pathway research focuses on identification of downstream components, the mechanism of receptor function, and control of the signaling pathway through the availability and amount of the ERECTA protein. A wide variety of methods are used in the lab, from whole plant morphology and cell biology to molecular biology, genetics, and biochemistry.

Selected Publications:

• Pillitteri L.J., Bemis S.M., Shpak, E.D., and Torii K.U. (2007) Haploinsufficiency after successive loss of signaling reveals a role for ERECTA-family genes in Arabidopsis ovule development. Development, 1341(17) p3099-3109


• Shpak, E.D., McAbee J.M., Pillitteri L.J., Torii K.U. (2005) Stomatal patterning and differentiation by synergistic interactions of receptor kinases. Science, 309(5732) p290-3


• Shpak, E.D., Berthiaume C.T., Hill E.J., Torii K.U. (2004) Synergistic interaction of three ERECTA-family receptor-like kinases controls Arabidopsis organ growth and flower development by promoting cell proliferation. Development. 131(7) p.1491-1501.


• Shpak, E.D., Lakeman M.B., and Torii, K.U. (2003) Dominant-negative receptor uncovers modes of action and redundancy in the Arabidopsis ERECTA LRR-RLK signaling pathway that regulates organ shape. Plant Cell 15 p.1095-1110.


• Torii, K. U., Hanson, L. A., Josefsson, C. A. B. and Shpak, E. D. (2003). Regulation of inflorescence architecture and organ shape by the ERECTA gene in Arabidopsis. In Morphogenesis and Patterning in Biological Systems (ed. T. Sekimura), pp. 153-164. Tokyo, Japan: Springer-Verlag.