School of Life Science, Peking University

Research Interests

Molecular mechanisms of ethylene signal transduction and interactions among plant hormones and other signals in Arabidopsis
Hormonal regulation in plant senescence
Small RNA and RNA decay in plant hormone signaling
Plant functional genomics and proteomics

Our scientific interest is to understand the mechanisms of phytohormone ethylene signal transduction and the interplays among ethylene and multiple signaling pathways in plant development, senescence and stress responses. Over the past years, we have been using Arabidopsis as a model system to study the signaling mechanisms of plant gaseous hormone, ethylene. Using a combination of genetics and genomics approaches, we have characterized a family of plant-specific transcription factors named EIN3 and EILs, among which EIN3 and EIL1 were shown to be essential in regulating ethylene responses. We found that the control of EIN3/EIL1 protein abundance is the essential step in plant response to ethylene, and two F-box proteins (EBF1/2) were identified to form functional SCF complexes to target EIN3 and EIL1 for degradation. Meanwhile, we have identified an exoribonuclease EIN5 that plays a positively regulatory role in the ethylene response pathway. Further analysis revealed that EIN5 acts to antagonize ubiquitin/proteasome-mediated EIN3 protein degradation by promoting RNA decay of EBF1 and EBF2 thru a small RNA-dependent pathway. Thus, our research works demonstrated two central regulatory mechanisms in the ethylene signal transduction pathway: SCF-mediated protein turnover and small RNA-mediated RNA decay. We have also found that ethylene exhibits comprehensive and complicated intersections with many other signaling pathways, including light, environmental stresses, pathogen infection, and other hormones, in a variety of plant development and defense processes. Hence, our goal is to delineate the underlying mechanisms of plant hormones (particularly ethylene) signal transduction and to uncover the regulatory network in the various cross-talks among hormones and other signals. Meanwhile, we will explore new route to systematically study plant signal transduction pathway using proteomics and functional genomics approaches.

Publications

Li, H. and Guo, H , Molecular basis of the ethylene signaling and response pathway in Arabidopsis , Journal of Plant Growth Regulation , 2007 , 26：89-210
Olmedo, G., Guo, H.,* Gregory, B., Nourizadeh, S., Aguilar-Henonin, L., Li, H., An, F., Guzman, P., and Ecker, J.R. , ETHYLENE-INSENSITIVE5 encodes a 5'→3' exoribonuclease required for posttranscriptional regulation of the EIN3-targeting F-box proteins EBF1/2 , Proc. Natl. Acad. Sci. USA , 2006 , 103: 13286-13293 , (* co-first author)
Guo, H. and Ecker, J.R. , The ethylene signaling pathway: new insights , Curr Opin Plant Biol , 2004 , 7: 40-49
Guo, H. and Ecker, J.R , Plant responses to ethylene gas are mediated by SCFEBF1/EBF2-dependent proteolysis of EIN3 transcription factor , Cell , 2003 , 115: 667-677
Shalitin, D., Yang, H., Mockler T., Maymon, M., Guo, H., Whitelam, G., and Lin, C , Regulation of Arabidopsis cryptochrome 2 by blue light-dependent phosphorylation , Nature , 2002 , 417: 763-767
Guo, H., Mockler, T., Duong, H., and Lin, C , SUB1, an Arabidopsis calcium-binding protein involved in cryptochrome and phytochrome co-action , Science , 2001 , 291: 487-490.
Guo, H., Duong, H., Ma, N., and Lin, C. , The Arabidopsis blue light receptor cryptochrome 2 is a nuclear protein regulated by a blue light-dependent post-transcriptional mechanism , Plant J. , 1999 , 19: 279-87
Mockler, T., Guo, H., Yang, H., Duong, H., and Lin, C. , Antagonistic actions of the Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction , Development , 1999 , 126: 2073-2082
Guo, H., Yang, H., Mockler, T., and Lin, C. , Regulation of flowering time by Arabidopsis photoreceptors , Science , 1998 , 279: 1360-1363.
Lin, C., Yang, H., Guo, H., Mockler, T., Chen, T., and Cashmore, A.R. , Enhancement of blue-light sensitivity of Arabidopsis seedling by a blue light receptor cryptochrome 2 , Proc. Natl. Acad. Sci. USA , 1998 , 95: 2686-2690

Hongwei Guo, Ph.D.

Research Interests

Publications