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The ability to respond to a vast array of external and internal cues such as light, gravity, and hormones is vital to the growth, development, and survival of plants. The mechanisms by which plants perceive these signals and convert the information into physiological changes are only beginning to be understood. We are focusing on signal transduction of the plant hormone ethylene (C2H4), a simple gas that has profound effects on plant growth and development. Our research utilizes a combination of molecular biology, genetics and cell biology in order to understand the molecular mechanisms of ethylene signaling. Our model system is the small flowering plant Arabidopsis thaliana, which is well-suited for molecular genetic approaches.

Arabidopsis has five related ethylene receptor genes in two subfamilies: ETR1 and ERS1 (subfamily 1) and ETR2 , EIN4 and ERS2 (subfamily 2). All encode homologs of the two-component histidine protein kinase family widely known in prokaryotes. Two-component histidine kinases perceive environmental stimuli and regulate responses through specialized phosphotransfer reactions. ETR1 was the first example of a two-component homolog among higher eukaryotes. Acting downstream of the receptors is a Raf-like serine/threonine protein kinase, CTR1, thought to act in a mitogen-activated protein (MAP) kinase cascade as in animals. Interestingly, the known signaling pathways leading to the activation of Raf in animals start with transmembrane tyrosine kinase receptors, whereas the ethylene response pathway in plants seem to regulate a Raf protein kinase in a new way, namely by a two-component-like receptors, which are primarily found in prokaryotes.

Our lab is one of a dozen research labs working with Arabidopsis at the University of Maryland at College Park (or nearby at University of Maryland at Baltimore County and Howard University). These labs comprise the Arabidopsis thaliana Research Initiative at the University of Maryland (ATRIUM). ATRIUM holds a monthly lab meeting as well as an annual Minisympoisum on Plant Biology for the mid-Atlantic region. Our lab also participates in a monthly lab meeting devoted to Genetics with Eukaryotic Model Systems (GEMS).
 

Projects
 

RTE1 and RTE1-HOMOLOG (RTH) - Genetic analysis, gene expression, and protein localization

Protein Interactions - Library screens and isolation of protein complexes

Caenorhabditis elegans - Analysis of the RTE1 ortholog

Regulation of Protein Kinase CTR1 - Investigation of regulatory mechanisms

Genetic Screens - Suppresors of etr1-2 and enhancers of ctr1-3
 

Caren Chang
Professor and Associate Department Chair
Ph.D. Caltech 1988
carenc@umd.edu

News

Apply to the Graduate Program: BISI

Graduate Studies in Plant Biology

Grad student John Clay receives poster award at UMD Bioscience Day 2012.

Recent Papers:

Ju C. et al. (2012) CTR1 phosphorylates EIN2 to control ethylene signaling from the ER membrane to the nucleus. PNAS 109: 19486-19491.
doi:10.1073/pnas.1214848109

Chen R. et al.(2011) Proteomic responses in Arabidopsis thaliana seedlings treated with ethylene, Mol. Biosys. 7:2637-2650..