R. Scott Poethig, Ph. D. Professor of Biology Ph.D., Yale University, 1980 103E Carolyn Lynch Laboratory Department of Biology University of Pennsylvania Philadelphia, PA 19104 USA V +1 215 898.8915 F +1 215 898.8780 E spoethig@sas.upenn.edu

Publication-qual. TIFF (~0.5 MB)

research : publications : education

genetic regulation of plant morphogenesis I am interested in the genetic regulation of morphogenesis in maize and Arabidopsis. Current research projects address the mechanism of vegetative phase change and the regulation of organ polarity. In addition, we are generating tools for the visualization and maninupulation of patterns of gene expression in Arabidopsis. phase change The morphology and physiology of the shoot system in plants change during development. Some of these changes are gradual, whereas others occur simultaneously at predictable times. This latter phenomenon is termed phase change, and is the primary focus of research in my laboratory. We are particularly interested in the transition from the juvenile to the adult phase of vegetative development, and have approached this problem by studying mutations that affect the timing of this transition in Arabidopsis and maize. Screens for precocious mutants have revealed that many genes involved in the biogenesis and function of miRNAs and endogenous siRNAs have this developmental phenotype. In addition to studying the cellular functions of these genes, we are using them as tools to identify the small RNAs involved in vegetative phase change. These studies have revealed that the trans-acting siRNA, tasi-ARF, and the miRNA, miR156, are particularly important, and we are working to understand their function in this process. Variation in leaf shape and the production of abaxial (yellow) and adaxial (red) trichomes along the length of the Arabidopsis shoot.   polarity In plants, the specification of dorsiventral polarity in lateral organs is linked to the specification of radial polarity in the shoot. Genes involved in this process have been identified by screening for mutations that affect the expression pattern of transgenic line that expresses Green Fluorescent Protein solely in the peripheral/abaxial domain of the shoot. These include mutations that produce an expansion of the central domain, and mutations that perturb the location of the boundary between the adaxial and abaxial domains. Studies to determine the molecular and developmental functions of the genes identified in this screen are in progress. Stereomicroscopic (left) and confocal (right) image of an Arabidopsis embryo with a transgene that is expressed in the abaxial domain of the shoot.

recent publications

Wu, G and R. S. Poethig (2006). Temporal regulation of shoot development in Arabidopsis by miR156 and its target SPL3. Development (in press)

Hunter, C, M. Willmann, G. Wu, M. Gutierrez-Nava and R. S. Poethig (2006). Trans-acting siRNA-mediated repression of ETTIN and ARF4 regulates heteroblasty in Arabidopsis. Development 133: 2973-2981.

Yoshikawa, M., Peragine, A., Park, M. Y. and R. S. Poethig (2005) A pathway for the biogenesis of trans-acting siRNAs in Arabidopsis. Genes & Dev. 19: 2164-2175.

Park, M. Y., Wu, G., Gonzalez-Sulser, A., Vaucheret, H. and R. S. Poethig (2005) Nuclear processing and export of microRNAs in Arabidopsis. Proc. Natl. Acad. Sci. 102: 3691-3696.

Willmann, M. R. and R. S. Poethig (2005) Time to grow up: the temporal role of small RNAs in plants. Curr. Op. Plant Biol. 8: 548-552.

Peragine, A., Yoshikawa, M., Wu, G., Albrecht, H. L. and R. S. Poethig (2004) SGS3 and SGS2/SDE1/RDR6 are required for juvenile development and the production of trans-acting siRNAs in Arabidopsis. Genes & Dev. 18: 2368-2379.

Poethig, R. S. (2003) Phase change and the regulation of developmental timing in plants. Science 301: 334-436.

Hunter, C., Sun, C., and R. S. Poethig (2003) The Arabidopsis heterochronic gene ZIPPY is an ARGONAUTE family member. Curr. Biol. 13: 1734-1739.

Bollman, K. M., Aukerman, M. J., Park, M. Y., Hunter, C., Berardini, T. Z., and R. S. Poethig. (2003) HASTY, the Arabidopsis ortholog of exportin 5/MSN5, regulates phase change and morphogenesis. Development 130: 1493-1504.

Hunter, C. and R. S. Poethig (2003) miSSING LINKS: miRNAs and plant development. Cur. Op. Cell Dev. Biol. 13: 372-378.

education

Ph.D., Yale University, 1980
M.A., Yale University, 1976
B.A., College of Wooster, 1974