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Abstract Detail


Hormone Biology

Sawyer, Rebecca [1], Mason, Michael [1], Mathews, Dennis [2], Palmer, Christine [1], Argyros, D. Aaron [1], Rashotte, Aaron [3], Kieber, Joseph [3], Schaller, G. Eric [4].

Arabidopsis type-B response regulators in cytokinin signaling.

Type-B Arabidopsis Response Regulators (ARR's) are transcription factors that act as positive regulators of the two-component cytokinin-signaling pathway in Arabidopsis. To characterize their role in plant growth and development, we isolated T-DNA insertion alleles in type-B ARR’s and constructed higher order mutant combinations. Single mutants were similar to wild type in phenotype, but higher order mutants showed increasing insensitivity to exogenously applied cytokinin. The most pronounced phenotype was found in an arr1,10,12 triple null mutant, which shows almost complete insensitivity to high levels of exogenously applied cytokinins. The triple mutant exhibits reduced stature due to decreased cell division in the shoot, sensitivity to light, altered chlorophyll and anthocyanin concentrations, and an aborted primary root with protoxylem but no metaxylem. Microarray analysis was used to determine the changes in expression that take place as a result of type-B ARR action, and how other transcription factors such as the Cytokinin Response Factors (CRF’s) act in tandem with the type-B ARR’s in cytokinin signaling. Our results support a model for cytokinin signaling in which multiple families of transcription factors positively regulate cytokinin responses.


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1 - Dartmouth College, Biological Sciences
2 - University of New Hampshire, Plant Biology
3 - University of North Carolina-Chapel Hill, Biology
4 - Dartmouth College, Biological Sciences, Hanover, NH, 03755, USA

Keywords:
Cytokinin
two-component
Transcription
response regulator.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P35046
Abstract ID:2676


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