Dr. Anna Stepanova - Assistant Professor
Hormone interactions, inter-tissue growth coordination, ethylene, auxin
Unlike mobile animals, sessile plants spend their lives in a fixed place and, being unable to move away, have to endure and withstand harsh conditions of their environment. To cope with this challenge, plants have learned to adapt to their surroundings by modifying their metabolic activity, growth rates and patterns. Our earlier work has focused on the elucidation of the role of two key plant hormones, auxin and ethylene, in the phenotypic plasticity of root growth and has uncovered a previously unknown ethylene-mediated regulation of auxin biosynthesis. Adequate levels of auxin production, perception, signaling, and response were found to be required for the ethylene-triggered morphological changes. Current efforts of the lab are focused on another intriguing (yet poorly understood) aspect of plant phenotypic plasticity: the ability of plants to maintain tight coordination of cell division/expansion between individual tissues of an organ regardless of the overall growth rate dictated by the environment and the plantʼs genotype. While it is widely accepted that the synchronized growth of tissues involves some type of cell-to-cell communication, the respective contribution of different tissues to organ growth and the nature of the inter-tissue interaction mechanism are currently unresolved. To address these long-standing controversial questions, we are utilizing a combination of transgenic approaches, cell biology, computational methods, and chemical, classical, and systems genetics to systematically dissect the mechanisms underlying inter-tissue growth coordination in leaves using Arabidopsis as a model system.
Pietra S., Gustavsson A., Kiefer C., Kalmbach L., Hörstedt P., Ikeda Y., Stepanova A., Alonso JM, Grebe M (2013) Arabidopsis SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity, Nat Commun 2013 Nov 15;4:2779. doi: 10.1038/ncomms3779.
Robert H.S., Grones P., Stepanova A.N., Robles L.M., Lokerse A.S., Alonso J.M., Weijers D., Friml J. (2013) Local auxin sources orient apical-basal axis in Arabidopsis embryos. Curr Biol (In press).
Stepanova A.N., Yun J., Robles L.M., Novak O., He W., Guo H., Ljung K., Alonso J.M. (2011) The Arabidopsis YUCCA1 Flavin Monooxygenase Functions in the Indole-3-Pyruvic Acid Branch of Auxin Biosynthesis, Plant Cell. 23(11):3961-73.
He W., Brumos J., Li H., Ji Y., Ke M., Gong X., Zeng Q., Li W., Zhang X., An F., Wen X., Li P., Chu J., Sun X., Yan C., Yan N., Xie D.Y., Raikhel N., Yang Z., Stepanova A.N., Alonso J.M., Guo H. (2011) A Small-Molecule Screen Identifies L-Kynurenine as a Competitive Inhibitor of TAA1/TAR Activity in Ethylene-Directed Auxin Biosynthesis and Root Growth in Arabidopsis. Plant Cell. 23(11):3944-60.
Zhou R., Benavente L.M., Stepanova A.N,. Alonso J.M. (2011) A recombineering-based gene tagging system for Arabidopsis. Plant J. 66(4):712-23.
Ikeda Y., Men S., Fischer U., Stepanova A.N., Alonso J.M., Ljung K., and Grebe M. (2009) Local auxin biosynthesis modulates gradient-dependent planar polarity in Arabidopsis. Nature Cell Biol. 11:731-738.
Stepanova A.N.*, Robertson-Hoyt J.,* Yun J., Benavente L.M., Xie D., Dolezal K., Schlereth A., Jurgens G., and Alonso J.M. (2008) TAA1-mediated auxin biosynthesis is essential for hormone crosstalk and plant development. Cell. 133:177-191 (*equal contribution).
Stepanova A.N., Yun J., Likhacheva A.V., Alonso J.M. (2007) Multilevel Interactions between Ethylene and Auxin in Arabidopsis Roots. Plant Cell. 19: 2169-2185.
Stepanova A.N., Hoyt J.M., Hamilton A.A., Alonso J.M. (2005) A Link between ethylene and auxin uncovered by the characterization of two root-specific ethylene-insensitive mutants in Arabidopsis. Plant Cell. 17:2230-42.
Alonso, J.M., Stepanova, A.N., Leisse, T.J., Kim, C.J., Chen, H., Shinn, P., Stevenson, D.K., Zimmerman, J., Barajas, P., Cheuk, R., Gadrinab, C., Heller, C., Jeske, A., Koesema, E., Meyers, C.C., Parker, H., Prednis, L., Ansari, Y., Choy, N., Deen, H., Geralt, M., Hazari, N., Hom, E., Karnes, M., Mulholland, C., Ndubaku, R., Schmidt, I., Guzman, P., Aguilar-Henonin, L., Schmid, M., Weigel, D., Carter, D.E., Marchand, T., Risseeuw, E., Brogden, D., Zeko, A., Crosby, W.L., Berry , C.C., Ecker, J.R. (2003) Genome-Wide Insertional Mutagenesis of Arabidopsis thaliana. Science 301: 653-657.