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Plant Biology Home

Phone: (612) 625-1234
Fax: (612) 625-1738

Department of Plant Biology
University of Minnesota
250 Biological Science Center
1445 Gortner Ave.
St. Paul, MN 55108

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William M. Gray

Associate Professor, Department of Plant Biology
Ph.D. University of Iowa, 1995.

Molecular basis of auxin-regulated growth and development; ubiquitin-mediated proteolysis

Contact Information

Mailing Address:

Dr. William Gray
Department of Plant Biology
University of Minnesota
250 Biological Science Center
1445 Gortner Ave.
St. Paul, MN 55108

Office: 674 Biological Sciences Center
Phone: 612-624-3042
Fax: 612-625-1738
E-mail: grayx051@umn.edu

Research Interests

The plant hormone auxin regulates virtually every aspect of plant growth and development. Much of this control occurs by auxin regulating the fundamental processes of cell division, cell expansion, and cell differentiation. Given the prominent role of auxin in these basic cellular events, it is hardly surprising that plant biologists have long been intrigued by this hormone and have compiled an enormous amount of physiological data concerning the responses of plants to applied auxin. Nonetheless, the mechanisms by which auxin functions have remained elusive.

We are using genetic, molecular, and biochemical approaches with Arabidopsis to investigate how auxin regulates plant growth and development. Recent findings have implicated the SCF^TIR1 ubiquitin-ligase complex as playing a central role in the auxin response pathway. In response to auxin, SCF^TIR1 catalyzes the ubiquitin-mediated degradation of members of the Aux/IAA protein family. The degradation of these negative regulators of auxin response derepresses the pathway, resulting in auxin-mediated changes in plant growth and development. We are currently pursuing how auxin regulates the interaction between SCF^TIR1 and the Aux/IAA proteins and the identification of upstream factors in the auxin response pathway

Selected Publications

Moon, J., Y.Zhao, X. Dai, W. Zhang, W.M. Gray, E. Huq, and M. Estelle. 2006. A new CUL1 mutant has altered responses to hormones and light in Arabidopsis. Plant Physiol. 143: 684-96.

Quint, M. and W.M. Gray. 2006. Auxin signaling. Curr. Opin. in Plant Biol. 9: 448-453.

Ito, H, and W.M. Gray. 2006. A gain-of-function mutation in the Arabidopsis pleiotropic drug resistance transporter PDR9 confers resistance to auxinic herbicides. Plant Physiol. 142: 63-74.

Quint, M., Ito, H., Zhang,W., and W.M. Gray. 2005. Characterization of a novel temperature-sensitive allele of the CUL1/AXR6 subunit of SCF ubiquitin-ligases.  Plant J. 43:371-383.

Chuang, H.-w., Zhang, W., and W.M. Gray. 2004 Arabidopsis ETA2, an Apparent Ortholog of the Human Cullin-Interacting Protein CAND1, Is Required for Auxin Responses Mediated by the SCF TIR1 Ubiquitin Ligase. Plant Cell, 16: 1883-1897.

Gray, W.M., P.R. Muskett, H.-w. Chuang, and J. E. Parker Arabidopsis SGT1b is required for SCF^TIR1 -mediated auxin response. Plant Cell, 15:1310-1319.

Gray, W.M., S. Kepinski, D. Rouse, O. Leyser, and M. Estelle. 2001. Auxin Regulates SCF^TIR1 -Dependent Degradation of Aux/IAA proteins. Nature 414, 271-276

Gray, W.M., Hellmann, H., Dharmasiri, S., and Estelle, M.. (2002). Role of the Arabidopsis RING-H2 protein RBX1 in RUB modification and SCF function. Plant Cell 14(9) 2137-2144.

Schwechheimer C., G. Serino, J. Callis, W.L. Crosby, S. Lyapina, R.J. Deshaies, W.M. Gray, M. Estelle, and X.W. Deng. 2001. Interactions of the COP9 Signalosome with the E3 Ubiquitin Ligase SCF^TIR1 in Mediating Auxin Response. Science 292, 1379-1382.

Gray, W.M., and M. Estelle. 2000. Function of the ubiquitin-proteasome pathway in auxin response. Trends Biol. Sci. 25: 133-138.

Gray, W.M., J.C. del Pozo, L. Walker, L. Hobbie, E. Risseeuw, T. Banks, W.L. Crosby, M. Yang, H. Ma, and M. Estelle. 1999. Identification of an SCF ubiquitin-ligase complex required for auxin response in Arabidopsis thaliana. Genes &; Dev. 13: 1678-1691.

Gray, W.M., A. Ostin, G. Sandberg, C.P. Romano, and M. Estelle. 1998. High temperature promotes auxin-mediated hypocotyl elongation in Arabidopsis. Proc. Natl. Acad. Sci. USA. 95: 7197-7202.

Ruegger, M., E. Dewey, W.M. Gray, L. Hobbie, J. Turner, and M. Estelle. 1998. The ^TIR1 protein of Arabidopsis functions in auxin response and is related to human SKP2 and yeast Grr1p. Genes & Dev. 12:198-207.