Higher organisms undergo several significant transitions during their development. In plants, the best understood of these is the transition from a vegetative to a reproductive phase of shoot development. This transition is preceded by the juvenile-to-adult transition (vegetative phase change), during which the shoot undergoes changes in its vegetative morphology and physiology, and becomes reproductively competent. In contrast to the vegetative-to-reproductive transition, the mechanism of vegetative phase change is very poorly understood. Recent studies indicate that the temporally-regulated miRNA, miR156, plays a major role in this process: miR156 declines in abundance during vegetative phase change, and promotes the expression of the juvenile phase and represses the expression of the adult phase when constitutively expressed. Ten members of the SBP family of transcription factors in Arabidopsis (SPL genes) have target sites for miR156, and we hypothesize that the effect of miR156 on phase change is mediated by some or all of these SPL genes. We propose to 1) determine the developmental functions of these miR156-regulated SPL genes, 2) investigate the organization of the pathways in which miR156 and these SPL genes operate, and 3) identify the factors responsible for the temporal expression of miR156. These experiments will yield the first detailed picture of the molecular mechanism of vegetative phase change and provide significant new information about the regulation and function of small RNAs in plants.

Public Health Relevance

Defects in developmental timing underlie many human diseases and inherited disorders. A better understanding of the fundamental mechanism of developmental timing, and the role of small RNAs in this process, is essential for developing therapies for these problems in human health and development.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Development - 1 Study Section (DEV1)
Program Officer
Hoodbhoy, Tanya
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pennsylvania
Schools of Arts and Sciences
United States
Zip Code
Xu, Mingli; Hu, Tieqiang; Smith, Michael R et al. (2016) Epigenetic Regulation of Vegetative Phase Change in Arabidopsis. Plant Cell 28:28-41
Fouracre, Jim P; Poethig, R Scott (2016) The role of small RNAs in vegetative shoot development. Curr Opin Plant Biol 29:64-72
Xu, Yunmin; Guo, Changkui; Zhou, Bingying et al. (2016) Regulation of Vegetative Phase Change by SWI2/SNF2 Chromatin Remodeling ATPase BRAHMA. Plant Physiol 172:2416-2428
Hudson, Corey J; Freeman, Jules S; Jones, Rebecca C et al. (2014) Genetic control of heterochrony in Eucalyptus globulus. G3 (Bethesda) 4:1235-45
Gillmor, C Stewart; Silva-Ortega, Claudia O; Willmann, Matthew R et al. (2014) The Arabidopsis Mediator CDK8 module genes CCT (MED12) and GCT (MED13) are global regulators of developmental phase transitions. Development 141:4580-9
Poethig, R Scott (2013) Vegetative phase change and shoot maturation in plants. Curr Top Dev Biol 105:125-52
Yang, Li; Xu, Mingli; Koo, Yeonjong et al. (2013) Sugar promotes vegetative phase change in Arabidopsis thaliana by repressing the expression of MIR156A and MIR156C. Elife 2:e00260
Yoshikawa, Manabu; Iki, Taichiro; Tsutsui, Yasuhiro et al. (2013) 3' fragment of miR173-programmed RISC-cleaved RNA is protected from degradation in a complex with RISC and SGS3. Proc Natl Acad Sci U S A 110:4117-22
Yang, Li; Wu, Gang; Poethig, R Scott (2012) Mutations in the GW-repeat protein SUO reveal a developmental function for microRNA-mediated translational repression in Arabidopsis. Proc Natl Acad Sci U S A 109:315-20
Earley, Keith W; Poethig, R Scott (2011) Binding of the cyclophilin 40 ortholog SQUINT to Hsp90 protein is required for SQUINT function in Arabidopsis. J Biol Chem 286:38184-9

Showing the most recent 10 out of 32 publications