by the NSF IBN Program and the NIH
Auxin is an essential
plant hormone that regulates diverse processes, such
as cell division and expansion, embryogenesis, meristem
formation, root and leaf patterning, tropism, and reproduction.
Extensive molecular studies have identified a large
set of auxin inducible genes and the auxin responsive
cis-elements and the relevant trans-acting factors.
Genetic approaches have led to the isolation of genes
involved in auxin responses and transport and the unraveling
of protein degradation control in auxin signaling.
lab has been interested in understanding the molecular
and biochemical mechanisms underlying the auxin signal
transduction pathway that control nuclear gene transcription
and plant morphogenesis. We have taken novel molecular
genetic and genomic approaches to identify regulatory
genes important for auxin-inducible transcription and
morphogenesis by using tobacco and Arabidopsis as model
systems. We have established efficient transient and
stable transformation systems that will allow the identification
of genes that can perturb (both gain-of-function and
loss-of-function) various steps of the auxin- dependent
transcription and morphogenesis, including cell proliferation,
elongation, and differentiation. These expression cloning
and functional genomic analysis methods could facilitate
the identification of genes involved in cell shape,
growth polarity, cell division, cell death, organogenesis,
embryogenesis and gene expression. The use of the jellyfish
green-fluorescent protein (GFP) provides an excellent
visual marker to follow auxin responses in living cells.
The experimental design can overcome lethality and functional
redundancy, which may limit the isolation of more specific
mutants important for the elucidation of the auxin signal
Based on the
control of early response gene transcription, we have
explored the functions of mitogen activated protein
kinase (MAPK) signaling cascades in the regulation of
auxin responses. We have discovered both positive and
negative roles of MAPK cascades in auxin signaling.
The future goals are to define the specific roles of
each molecular component and their upstream regulators
and downstream targets. In addition, our studies have
revealed surprising connections between auxin and stress
signaling as well as auxin and sugar signaling in plants.
The identification of molecular links connecting auxin
and sugar, stress or cytokinin signaling networks will
reveal a complex but more realistic view of regulatory
circuits in plant cells. The studies have provided novel
approaches to manipulate plant life span, seed development,
and vegetative and reproductive growth for the improvement
of crop yield.
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Yoo, S.D., Cho, Y.H.,, and Sheen, J. 2009.
Emerging connections in the ethylene-signaling network. Trends in Plant Science. 14: 270-279.PDF
Ramon, M., Rolland, F., and Sheen, J. October 22, 2008
Sugar Sensing and Signaling. The Arabidopsis Book (TAB), ISSN: 1543-8120 http://www.aspb.org/publications/arabidopsis/ pages 1-22 PDF
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molecule. Curr. Opin. Plant Biol. 2:410-418.
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Shan, L., He, P., Li, J., Heese, A., Peck, S.C., Nürnberger, T., Martin, G.B. and Sheen, J. 2008.
Bacterial Effectors Target the Common Signaling Partner BAK1 to Disrupt Multiple MAMP Receptor Signaling Complexes and Impede Plant Immunity. Cell Host & Microbe 4: 17-27 PDF  SUPP
Müller, B. and Sheen, J. 2008.
Cytokinin and auxin interaction in root stem-cell specification during early embryogenesis. Nature 453: 1094-1097 PDF  SUPP
Yoo, S-D., Cho Y-H., Tena G., Xiong. Y. and Sheen, J. 2008.
Dual control of nuclear EIN3 by bifurcate MAPK cascades in C2H4 signalling.
Nature 451: 789-795 PDF  SUPP
Chen, Z., Agnew, J.L., Cohen, J.D., He, P., Shan, L., Sheen, J. and Kunkel, B.N. 2007.
Pseudomonas syringae type III effector AvrRpt2 alters Arabidopsis thaliana auxin physiology.
PNAS 104: 20131-20136 PDF
B., Zhou, L.,Rolland, F., Hall, Q., Cheng, W.-H., Liu, Y.-X., Hwang, I.,
Jones, T., Sheen, J. 2003. Role of the Arabidopsis Glucose Sensor HXK1 in Nutrient,
Light, and Hormonal Signaling. Science 300: 332-336 Abstract
I. and Sheen, J. 2001. Two-component circuitry in Arabidopsis
cytokinin signal transduction. Nature 413(6854):383-9 PDF
Y., Chiu, W.-L. Tena, G., and Sheen, J. 2000. Functional
analysis of oxidative stress-activated MAPK cascade in plants.
PNAS. 97: 2940-2945.
J., Fujioka, S., Tasaka, M., Seto, H., Takatsuto, S.,
Ishii, A., Aida, Yoshida, S., Sheen, J. 2000. A critical role
of sterols in embryonic patterning and meristem programming
revealed by the fackel mutants of Arabidopsis thaliana. Genes
& Dev. 14: 1485-1497.
Y., Chiu, W.-L. Zeng, W. and Sheen, J. 1998. Suppression
of auxin signal transduction by a MAPK cascade in higher plants.
Nature 395: 716-720.
W.-L. , Niwa, Y, Zeng, W, Hirano, T., Kobayashi, H, Sheen,
J. 1996. Engineered GFP as a vital reporter in plants. Current
Biol. 6: 325-330.
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