Dr. Tierney received her Ph.D. in Genetics under the direction of Karel Schubert at Michigan State University and then did postdoctoral research with Roger Beachy and Joseph Varner at Washington University. She was a faculty member at Ohio State before coming to the University of Vermont in 1992.

Mary has been the Director of the CMB Program since July of 2009.

The dynamic character of the plant cell wall provides a mechanism(s) by which plants selectively modify their extracellular matrix as a consequence of growth and differentiation. My research group is interested in understanding the mechanisms through which structural proteins within the plant cell wall determining aspects of cell form and function during plant development.

We are currently studying a family of proline-rich cell wall proteins in Arabidopsis (AtPRPs) whose function is involved in tailoring the structure of the plant cell wall in root hairs and stomata. We have used promoter/reporter gene fusions in transgenic plants to show that the expression of individual AtPRPs is limited to these cell types and is linked to factors that control cell growth.

Studies in my lab have shown that each of the four ATPRPs is targeted to a specific region of the extracellular matrix, using immunohistochemistry. We have also identified knock-out mutants for each of these proteins. Null mutants for the two proteins expressed in root hairs (ATPRP1 and ATPRP3) present distinct root hair and whole plant phenotypes, suggesting that these proteins may serve different functions in organizing the structure of the primary cell wall. Future studies will focus on identifying changes in gene expression between wild type and mutant plants that would explain the developmental phenotypes observed in these mutants.

We have also identified regions within each of the AtPRPs that are sufficient for their targeted secretion to unique regions within root hair and guard cell walls. In the future, we are interested in identifying components of the secretory pathway that are responsible for these targeting mechanisms and which provide a mechanism for selectively tailoring domains of the extracellular matrix to support cell function.

Fowler, T.J., Bernhardt, C., Tierney, M.L. Characterization and expression of four proline-rich cell wall protein genes in Arabidopsis encoding two distinct subsets of multiple domain proteins. Plant Physiol. 1999 Dec;121(4):1081-1092.

Bernhardt, C., Tierney, M.L. Expression of AtPRP3, a proline-rich structural cell wall protein from Arabidopsis, is regulated by cell-type-specific developmental pathways involved in root hair formation. Plant Physiol. 2000 Mar;122(3):705-714.

Bernhardt, C., Tierney, M.L. (2006) Proline-rich cell wall proteins building blocks ofr an expanding cell wall In The Science and Lore of the Plant Cell wall: Biosynthesis, Structure and Function. Brown Walker Press, Boca Raton, FL pp164 ?170

Hu, J., Tierney, M.L. AtPRP3 protein localizes to the cell wall of the growing tip of root hairs in Arabidopsis. In preparation.

Bernhardt, C., Tierney, M.L. AtPRP4 expression is linked to lateral root and guard cell development.

* indicates equal contribution