Plants change as they develop. Some of these changes occur gradually over a long period of time, whereas others occur quickly, often resulting in major changes in shoot morphology. This latter phenomenon is termed phase change, and is the primary focus of our research. We are particularly interested in the juvenile-to-adult transition, also known as vegetative phase change. This transition precedes flowering, and is characterized by changes in shoot architecture and patterns of cellular differentiation, by an increase in reproductive competence, and by changes in a variety of physiological processes. Vegetative phase change is promoted by a group of plant-specific transcription factors (SBP/SPL proteins), whose expression is repressed during the juvenile phase by the miRNAs, miR156 and miR157. Vegetative phase change occurs when the levels of miR156/miR157 decline, leading to an increase in the abundance of SBP/SPL proteins. We are studying the temporal regulation of miR156/miR157 and the organization and function of the pathways they control.
We work primarily with Arabidopsis thaliana, but have recently begun to explore the mechanism and evolution of vegetative phase change in the Acacieae, a pantropical family of nitrogen-fixing trees that includes species that do, and do not, undergo major morphological changes during vegetative phase change. In addition to studying the timing of vegetative phase change, we are interested in the molecular mechanism by which miR156/miR157 regulate gene expression, and have identified a number of genes involved in this process.
Xu, M., Hu, T., Zhao, J., Park, M-Y, Earley, K.W., Wu, G., Yang, L., R. S. Poethig (2016). Developmental functions of miR156-regulated SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes in Arabidopsis thaliana. PLoS Genetics 12(8): e1006263
Xu, M., Hu, T., Smith, M. R. and R. S. Poethig (2016). Epigenetic regulation of vegetative phase change in Arabidopsis. Plant Cell 28: 28-41.
Fouracre, J. P. and R. S. Poethig (2016) The role of small RNAs in vegetative shoot development. Curr. Op. Plant Biol. 29: 64-72.
Wu, G., Rossidivito, G., Hu, T., Berlyand, Y., and R. S. Poethig (2015). Traffic lines: new tools for genetic analysis in Arabidopsis thaliana. Genetics 200: 35-45
Gillmor, C. S, Silva-Ortega, C. O., Willmann, M. R., Buendîa-Monreal, M., and R. S. Poethig (2014). The Arabidopsis Mediator CDK8 module genes CCT (MED12) and GCT (MED13) are global regulators of developmental phase transitions. Development 141:4580-4589
Hudson, C. J., Freeman, J. S., Jones, R. C., Potts, B. M., Wong, M.M., Weller, J. L., Hecht, V. F., Poethig, R. S., and R. E. Vaillancourt. (2014). Genetic control of heterochrony in Eucalyptus globulus. G3 8: 1235-1245.
Poethig, R. S. (2013) Vegetative phase change and shoot maturation in plants. In: Current Topics in Developmental Biology 105: 125-152
Yang, L., Xu, M., Koo, Y., He, J., and R. S. Poethig (2013). Sugar promotes vegetative phase change in Arabidopsis thaliana by repressing the expression of MIR156A and MIR156C. eLife 2:e00260
Yang, L. and R. S. Poethig (2012). Mutations in the GW-repeat protein SUO reveal a developmental function for miRNA-mediated translational repression in Arabidopsis. Proc. Natl. Acad. Sci 109:315-320.
Earley, K. W. and R. S. Poethig (2011). Binding of the Cyclophilin 40 ortholog SQUINT to HSP90 protein is required for SQUINT function in Arabidopsis. J. Biol. Chem. 286: 38184-38189.
Wang, J-W., Park, M. Y., Wang, L-J., Koo, Y., Chen, X-Y., Weigel, D. and R. S. Poethig (2011) miRNA control of vegetative phase change in trees. PLoS Genetics 7:e1002012.
Willmann, M. R. and R. S. Poethig (2011) The effect of the floral repressor FLC on the timing and progression of vegetative phase change in Arabidopsis. Development 138: 677-685.
Yang, L., Conway, S. R. and R. S. Poethig (2011). Vegetative phase change is mediated by a leaf-derived signal that represses the transcription of miR156. Development 138: 245-249.
Biology 17: The Biology of Food
Biology 101: Introductory Biology
Biology 540/CAMB541: Genetic Analysis