Symposium III: Hormone Crosstalk
Abs #
30001: Cytokinin signaling and its interactions with ethylene and light
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Presenter: |
Kieber, Joseph J, jkieber@unc.edu |
Authors | Kieber, Joseph J (A) To, Jennifer (A) Haberer, Georg (A) Maxwell, Bridey (A) Rashotte, Aaron (A) McCasland, Michael (A) Chae, Hyun Sook (A) Hutchison, Claire (A) | | Affiliations: |
(A): University of North Carolina, Department of Biology
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| Web Site: | http://www.bio.unc.edu/faculty/kieber/ | |
Plant signaling pathways interact to regulate growth and development. Multiple hormone inputs are integrated to achieve a coordinated response to various environmental and developmental cues. This integration occurs at multiple points, including through the regulation of hormone levels, crosstalk in signal transduction pathways and overlapping transcriptional responses. Cytokinins have been implicated a wide variety of plant growth and development processes, and have been shown to interact with various other signals. Recent studies have demonstrated that cytokinin signal transduction occurs through a classic bacterial two-component signaling system. Using molecular, genetic and biochemical approaches, we have defined the role of the Arabidopsis two-component genes in cytokinin signaling. A major thrust of our research efforts has been an analysis of loss-of-function alleles of the approximately 35 two-component like genes in Arabidopsis. There is extensive functional redundancy in these gene families. Analysis of lines harboring multiple disruptions has indicated the role that these genes play in cytokinin signaling. Mutations in these elements also affect the response of seedlings to light, highlighting the interactions between light and cytokinin signaling.
We have also analyzed the interaction between ethylene and cytokinin. Cytokinin application elevates ethylene biosynthesis in etiolated Arabidopsis seedlings. Molecular genetic analysis has shown that this is the result of a stabilization of the ACS5 protein, which is one of twelve Arabidopsis ACC synthases, enzymes that catalyze the rate-limiting step in ethylene biosynthesis. ACS5 protein is targeted to the 26S proteosome via a C-terminal targeting sequence, and several components involved in this targeting have been identified. The regulation of the stability of ACS proteins may be a general mechanism by which plants control the level of ethylene biosynthesis.
