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Are the metabolic components of crassulacean acid metabolism up-regulated in response to an increase in oxidative burden?
J Exp Bot. 2006; 57(2):319-28.JE

Abstract

In the halophytic species Mesembryanthemum crystallinum, crassulacean acid metabolism (CAM) may be induced by a range of abiotic factors including drought, salinity, high light intensity, low temperature, and anoxia. A key biotic consequence of all these environmental changes is the generation of reactive oxygen species in planta that can elicit potentially damaging oxidative reactions and/or act as signals for engaging mechanisms that alleviate oxidative stress. However, induction of CAM per se also has the potential for increasing the oxidative burden via the enhanced internal O2 concentrations that develop behind closed stomata during daytime decarboxylation. The aim of this paper was to test two hypotheses. The first one, that reactive oxygen species are key signals for up-regulating the major genes and proteins required for the operation of CAM as part of an integrated strategy for alleviating oxidative burden, was tested using gaseous ozone to increase the oxidative burden at a cellular level. The second hypothesis, that CAM potentially increases oxidative load, was tested using a CAM-deficient mutant of M. crystallinum. The data indicate that ozone, like salinity, elicits an increase in the transcript and protein abundance of myo-inositol o-methyl transferase (a key enzyme of cyclitol synthesis), together with phosphoenolpyruvate carboxylase and other 'CAM-related' enzymes. However, ozone, unlike salinity, does not induce functional CAM, implying that the various metabolic components required for CAM respond to different signals. Comparing the activities of different subcellular isoforms of superoxide dismutase in wild-type and CAM-deficient mutants of M. crystallinum suggests that the induction of CAM potentially curtails the oxidative load in planta.

Authors+Show Affiliations

Borland A
School of Biology, Institute for Research on the Environment and Sustainability, Devonshire Building, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK. a.m.borland@ncl.ac.uk
Elliott S
No affiliation info available
Patterson S
No affiliation info available
Taybi T
No affiliation info available
Cushman J
No affiliation info available
Pater B
No affiliation info available
Barnes J
No affiliation info available

MeSH

Gene Expression Regulation, PlantMesembryanthemumMethyltransferasesOxidative StressOzonePhosphoenolpyruvate CarboxylasePhotosynthesisPlant ProteinsReactive Oxygen SpeciesSignal TransductionSodium ChlorideSuperoxide Dismutase

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

16356942

Citation

Borland, Anne, et al. "Are the Metabolic Components of Crassulacean Acid Metabolism Up-regulated in Response to an Increase in Oxidative Burden?" Journal of Experimental Botany, vol. 57, no. 2, 2006, pp. 319-28.
Borland A, Elliott S, Patterson S, et al. Are the metabolic components of crassulacean acid metabolism up-regulated in response to an increase in oxidative burden? J Exp Bot. 2006;57(2):319-28.
Borland, A., Elliott, S., Patterson, S., Taybi, T., Cushman, J., Pater, B., & Barnes, J. (2006). Are the metabolic components of crassulacean acid metabolism up-regulated in response to an increase in oxidative burden? Journal of Experimental Botany, 57(2), 319-28.
Borland A, et al. Are the Metabolic Components of Crassulacean Acid Metabolism Up-regulated in Response to an Increase in Oxidative Burden. J Exp Bot. 2006;57(2):319-28. PubMed PMID: 16356942.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Are the metabolic components of crassulacean acid metabolism up-regulated in response to an increase in oxidative burden? AU - Borland,Anne, AU - Elliott,Stewart, AU - Patterson,Susan, AU - Taybi,Tahar, AU - Cushman,John, AU - Pater,Beata, AU - Barnes,Jeremy, Y1 - 2005/12/15/ PY - 2005/12/17/pubmed PY - 2006/3/2/medline PY - 2005/12/17/entrez SP - 319 EP - 28 JF - Journal of experimental botany JO - J Exp Bot VL - 57 IS - 2 N2 - In the halophytic species Mesembryanthemum crystallinum, crassulacean acid metabolism (CAM) may be induced by a range of abiotic factors including drought, salinity, high light intensity, low temperature, and anoxia. A key biotic consequence of all these environmental changes is the generation of reactive oxygen species in planta that can elicit potentially damaging oxidative reactions and/or act as signals for engaging mechanisms that alleviate oxidative stress. However, induction of CAM per se also has the potential for increasing the oxidative burden via the enhanced internal O2 concentrations that develop behind closed stomata during daytime decarboxylation. The aim of this paper was to test two hypotheses. The first one, that reactive oxygen species are key signals for up-regulating the major genes and proteins required for the operation of CAM as part of an integrated strategy for alleviating oxidative burden, was tested using gaseous ozone to increase the oxidative burden at a cellular level. The second hypothesis, that CAM potentially increases oxidative load, was tested using a CAM-deficient mutant of M. crystallinum. The data indicate that ozone, like salinity, elicits an increase in the transcript and protein abundance of myo-inositol o-methyl transferase (a key enzyme of cyclitol synthesis), together with phosphoenolpyruvate carboxylase and other 'CAM-related' enzymes. However, ozone, unlike salinity, does not induce functional CAM, implying that the various metabolic components required for CAM respond to different signals. Comparing the activities of different subcellular isoforms of superoxide dismutase in wild-type and CAM-deficient mutants of M. crystallinum suggests that the induction of CAM potentially curtails the oxidative load in planta. SN - 0022-0957 UR - https://www.unboundmedicine.com/medline/citation/16356942/Are_the_metabolic_components_of_crassulacean_acid_metabolism_up_regulated_in_response_to_an_increase_in_oxidative_burden DB - PRIME DP - Unbound Medicine ER -