Symposium II: Reactive oxygen species: balancing signaling and stress
Abs #
20001: Regulated Rop GTPase signaling in response to hypoxia – Is survival a balancing act?
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Presenter: |
Bailey-Serres, Julia , serres@ucr.edu | Authors | Bailey-Serres, Julia (A) Baxter-Burrell, Airica (A) Branco Price, Cristina (A) Chang, Ruth (A) Fukao, Takeshi (A) | | Affiliations: |
(A): Center for Plant Cell Biology, Botany and Plant Sciences Department, University of California, Riverside, 92521
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| Web Site: | http://www.cepceb.ucr.edu/ | |
Plants respond to molecular oxygen deficiency through altered cellular gene expression and metabolism. Species and organs that survive or succumb to transient submergence differ in the timing and duration of carbohydrate consumption and anaerobic metabolism. The increased production of alcohol dehydrogenase (ADH), which is required for anaerobic fermentation, paradoxically involves the formation of reactive oxygen species in Arabidopsis thaliana and rice (Oryza sativa). Hypoxia promotes activation of a RHO of plants (Rop) G-protein and a diphenylene iodonium (DPI)-sensitive enzyme that leads to an increase in hydrogen peroxide levels measured in crude cell extracts. The activation of this signaling pathway is required for the hypoxia-mediated induction of ADH mRNA, as well as increases in steady-state accumulation in the mRNA that encodes Rop GTPase activating protein4 (ROPGAP4), a negative regulator of Rop signaling [1]. The examination of mutants with altered regulation of Rop signaling have revealed that hydrogen peroxide acts as in both the positive and negative regulation of Rop signaling in response to this stress. Tolerance of oxygen deficiency requires both feed-forward activation and negative-feedback attenuation of Rop signaling. We propose that a Rop rheostat that regulates production of signaling-competent reactive oxygen species provides tolerance of oxygen deficiency through management of carbohydrate consumption and avoidance of oxidative stress. (1) Baxter-Burrell et al., Science 296(5575):2026-2028; Funded by the National Science Foundation and the US Department of Agriculture.
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