Hall, Brenda P. , Qu, Xiang , Gao, Zhiyong , Schaller, G. Eric .
The Role of ETR1 and ERS1 in Ethylene Signal Transduction.
The simple gaseous hormone Ethylene (C2H4) has profound effects upon plant growth and development. In Arabidopsis, ethylene is perceived by a receptor family consisting of five family members: ETR1, ERS1, ETR2, ERS2, and EIN4. The Ethylene receptors are further divided into subfamilies based on phylogenetic analysis and sequence similarities. ETR1 and ETR2 are subfamily 1 members and both have highly conserved his kinase domains. ETR2, ERS2 and EIN4 are subfamily 2 members and all lack the histidine kinase activity but may act as ser/threonine kinases. We isolated new T-DNA insertion alleles of subfamily 1 members ERS1 and ETR1, both of which are null mutations based on molecular, biochemical, and genetic analyses. These single mutants showed an ethylene response similar to wildtype. The ers1; etr1 double mutant, however, displayed a constitutive ethylene-response phenotype more pronounced than that observed with any previously characterized combination of ethylene receptor mutations. Dark-grown ers1; etr1 seedlings displayed a constitutive triple-response phenotype. Light-grown ers1; etr1 plants were dwarfed, largely sterile, exhibited premature leaf senescence, and developed novel structures at the base of the flower. A reduced level of ethylene response was still uncovered in the double mutant, indicating that subfamily 2 receptors can independently contribute to signaling, with evidence suggesting that this is due to their interaction with the Raf-like kinase CTR1. Our results are consistent with the ethylene receptors acting as redundant negative regulators of ethylene signaling, but with ETR1 and ERS1 of subfamily 1 receptors playing the predominant role. Continuing examination of these lines as well as other transgenic lines is in progress.
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1 - Dartmouth College, Department of Biological sciences, Gilman 6044, Hanover, NH, 03755, USA
2 - University of North Carolina at Chapel Hill, Department of Biological sciences
3 - California Institute of Technology, Department of Biological sciences
4 - Dartmouth College, Department of Biological Sciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM