JANE E. DORWEILER
Assistant Professor

B.A. 1991, University of Minnesota
Ph.D. 1996, University of Minnesota
Postdoctoral Fellow, University of Arizona

WLS 208
(414) 288-5120
email: jane.dorweiler@marquette.edu

Click on the Lab Webpage for more information about Dr. Dorweiler's research program, coursework and a complete list of publications.

Developmental Gene Regulation

The research in my lab is directed toward understanding the dynamic process of gene regulation during the development of an organism.  The roles of both epigenetic mechanisms and environmental influences in this process intrigue me.  I am further interested in exploring how evolution alters this developmental process, resulting in new forms or varied behavior.  All of the work in my lab originated as a characterization of the developmental phenotypes observed in two epigenetic mutants of maize, mediator of paramutation1 (mop1) and mop2.  The two primary developmental phenotypes for both mutations are delayed flowering and feminized tassels.  As a result of my efforts to characterize these effects, research in my lab is focused in two major areas: Flowering Time Regulation and Tassel Development. 

Flowering Time Regulation

The long-term goal of this research is to better comprehend flowering time regulation in maize.  We draw upon the wealth of data in Arabidopsis, and increasing data in rice, each of which reveal a complex network of interacting pathways.  The current focus of this project is on the role of photoperiod in maize flowering, and how that role has been altered during human selection for growth in a broader range of latitudes.  We have identified maize genes (conz1, gigz1A, and gigz1B) homologous to key photoperiod pathway genes (CONSTANS and GIGANTEA, respectively) that regulate flowering in Arabidopsis and rice.  We have found that conz1 exhibits distinct circadian expression patterns in different photoperiods, which was unexpected given that flowering of modern maize is frequently characterized as photoperiod insensitive.  Moreover, conz1 expression in maize shows variation relative to its expression in the wild progenitor of maize, teosinte, which requires short-days to flower.  Together, these data represent the first characterization of photoperiod genes in maize, and suggest that modern ‘day-neutral’ maize is able to discern variations in photoperiod (Miller, Muslin and Dorweiler, 2008). 

We continue to actively pursue this line of research on several fronts. Transgenic experiments are underway to determine whether conz1 can complement mutations in the Arabidopsis CONSTANS and rice Heading date1 (Hd1) homologs.  We are also pursuing several approaches to identify and assay the expression of putative targets of CONZ1, and to similarly test such target genes in transgenic Arabidopsis.  Finally, we are currently undertaking efforts to assay CONZ1 protein levels in maize samples to determine whether they correlate with observed mRNA levels, and assay putative upstream regulators of conz1 to identify gene(s) that may be responsible for altering the pattern of conz1 expression in long versus short-day photoperiod conditions. 

Tassel Development

Efforts to study the feminized tassel phenotype observed in mop1 mutants have led to the identification of several SBP-box genes that exhibit increased mRNA levels in feminized tassels, including those feminized tassels induced by a distinct mutation, tasselseed1 (ts1).  All of the affected SBP-box genes are putative targets for a specific microRNA (miR156), for which we observe decreased levels in the same feminized tassels.  We have proposed a model for normal sex-determination and tassel development that integrates disparate sex-determination genes and postulates several hypotheses, both with regard to potential roles for miR156 and miR172 in inflorescence development, and with regard to potential roles for various SBP-box genes in primary or secondary sex traits of the tassel versus the ear of maize (Hultquist and Dorweiler, in press). We are testing each of these hypotheses in an effort to better understand normal development in the ear and tassel of maize. Future efforts will be directed toward identifying putative downstream targets of the SBP-box genes, as well as determining the mechanism by which this suite of genes is activated in the feminized tassels of mop1 mutants. 

In summary, the overarching theme for research in my lab is maize inflorescence development, from the floral transition to subsequent sex-determination and proper ear versus tassel differentiation. Our long-term goal is to contribute greater understanding of proper gene regulation, both during development and within an evolutionary context.   

Selected References

Hultquist, J.F. and Dorweiler, J.E.  Feminized Tassels of Maize mop1 and ts1 Mutants Exhibit Altered Levels of miR156 and Specific SBP-box Genes Planta - in press.

Miller, T.A., Muslin, E.H., Dorweiler, J.E.  2008.  A maize CONSTANS-like gene, conz1, exhibits distinct diurnal expression patterns in varied photoperiods. Planta 227:1377-88.

Alleman, M., Sidorenko, L., McGinnis, K., Seshadri, V., Dorweiler, J.E., White, J., Sikkink, K., Chandler, V.L.  2006.  An RNA-dependent RNA polymerase is required for paramutation in maize. Nature 442: 295-8.

Dorweiler, J.E., Carey, C.C., Kubo, K.M., Hollick, J.B., Kermicle, J.L. and V.L. Chandler. 2000.  Mediator of paramutation-1 (mop1) is required for establishment and maintenance of paramutation at multiple maize loci. Plant Cell 12: 2101-2118.

Dorweiler, J.E. and J. Doebley.  1997.  Developmental analysis of teosinte glume architecture1: A key locus in the evolution of maize (Poaceae). Am. J. Botany 84: 1313-1322.

Dorweiler, J.E., Stec, A., Kermicle, J.L. and J. Doebley.  1993.  Teosinte glume architecture1: A genetic locus controlling a key step in maize evolution. Science 262: 233-235.