Christiansen, Katy , Innes, Roger .
Identification of Downstream Targets of EDR1, a Negative Regulator of Cell Death.
Cell death is an important component of many responses in plants, including disease resistance and senescence. EDR1 was identified in a screen for Arabidopsis thaliana mutants that showed enhanced resistance to the fungal pathogen Erysiphe cichoracearum. This resistance is characterized by lesions at the site of infection, which prevents the pathogen from reproducing. Additionally, edr1 mutants display early senescence in response to ethylene and increased sensitivity to drought, resulting in lesion formation and smaller plants. These responses indicate that EDR1 is a negative regulator of cell death in response to pathogen, drought, and hormone treatment. EDR1 encodes a protein containing a C-terminal kinase domain similar to CTR1 and four unknown proteins in Arabidopsis. To identify potential substrates of EDR1, the C-terminal kinase domain was used as bait for a yeast two-hybrid screen with an Arabidopsis protein library. Two potential interactors were identified, AtMYC2, an abscisic acid-inducible transcription factor, and KCA1, a kinesin-like protein. The EDR1 kinase domain co-immunoprecipitates with fragments of both proteins when transiently expressed in tobacco. Additionally, EDR1 protein can be detected in nuclear protein extracts, suggesting that the interaction with AtMYC2 may take place in the nucleus. Consistent with a role in ABA-inducible responses, edr1 mutants are more sensitive to ABA than wild type. When germinated on media containing ABA, edr1 germinates slower than wild type. The lesion formation and reduced growth observed in edr1 under drought conditions are also consistent with altered ABA responses. EDR1 may regulate ABA responses by phosphorylating AtMYC2, thus affecting the expression of ABA-responsive genes.
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1 - Indiana University, Biology, 150 Myers Hall, Indiana University, Bloomington, IN, 47405, USA
2 - Indiana University, Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM