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The role of ASCORBATE PEROXIDASE 2 in systemic signaling in Arabidopsis thaliana
Stockholm University, Faculty of Science, Department of Botany.
Institute of Plant Physiology, Polish Academy of Sciences, 30 239 Krakow, Poland.
Department of Plant Genetics, Breading and Biotechnology, Warsaw University of Life Sciences, 02-776 Warszawa, Poland.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Plants have to survive in a changing environment and adapt to different abiotic stresses like changes in light intensity or temperature, flooding and soil salinity. Stress conditions cause the increased production of reactive oxygen species (ROS). ROS detoxification requires the activity of different antioxidant systems, among them the H2O2 scavenging enzymes, ascorbate peroxidases (APXs). Many APX forms exist; specifically, a cytosolic APX2 whose expression is restricted to bundle sheath cells and is induced upon accumulation of H2O2 in the chloroplasts of these cells. While the regulation of APX2 expression is well examined, not much is known about its function. Here, the characterization of two APX2 knockout lines from Arabidopsis thaliana is described. The results indicated that APX2 activity does not affect resistance against excess light stress, but systemic signaling in response to excess light treatment.

Keyword [en]
reactive oxygen species, light stress, bundle sheath cells
National Category
Botany
Research subject
Plant Physiology
Identifiers
URN: urn:nbn:se:su:diva-30833OAI: oai:DiVA.org:su-30833DiVA: diva2:274340
Available from: 2009-10-28 Created: 2009-10-28 Last updated: 2010-01-14
In thesis
1. Control of reactive oxygen species homeostasis in response to environmental stress
Open this publication in new window or tab >>Control of reactive oxygen species homeostasis in response to environmental stress
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plants are exposed to various fluctuations in their environmental conditions - light intensity, temperature, water status - and have to adapt in order to survive. Plant acclimatory responses can include the formation of new tissues, e.g., aerenchyma, or the activation of defense systems, e.g., the ascorbate-glutathione cycle for detoxification of reactive oxygen species (ROS). A prominent ROS is hydrogen peroxide (H2O2), a non-radical molecule formed during the reduction of oxygen. Due to its non-radical nature, H2O2 is more stable than other ROS and this longevity makes it the most abundant ROS in the plant cell and potentially harmful. In spite of this, H2O2 is involved in several signal transduction processes in plant cells, e.g., in the control of stomatal aperture, in plant-symbiont- and in plant-pathogen interactions, also in programmed cell death (PCD). Therefore, it is important for plant cells to maintain a tight control of H2O2 levels.

In this study, the role of H2O2 production and -detoxification was studied in different plant processes. First, signaling leading to aerenchyma formation was studied in Arabidopsis thaliana. This plant shows lysigenous aerenchyma formation, a process involving PCD, which meant it was preceded by H2O2 formation. Second, the role of a H2O2 detoxifying enzyme, cytosolic ascorbate peroxidase 2 (APX2) from A. thaliana, in the local and systemic response to excess light stress, was studied by means of the characterization of APX2 knockout mutant lines. Third, antioxidant defense was studied in two types of nitrogen-fixing actinorhizal root nodules with different oxygen metabolism, from Datisca glomerata and Casuarina glauca. Fourth, the role of a plant natriuretic peptide from actinorhizal nodules of Alnus glutinosa, in abiotic stress resistance was studied.

Place, publisher, year, edition, pages
Stockholm: Department of Botany, Stockholm University, 2009. 51 p.
Keyword
Stress, antioxidant defense, ascorbate peroxidase, aerenchyma, actinorhiza
National Category
Botany
Research subject
Plant Physiology
Identifiers
urn:nbn:se:su:diva-30849 (URN)978-91-7155-967-8 (ISBN)
Public defence
2009-11-27, Föreläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defence, the following papers were unpublished and had a status as follows: Paer 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.Available from: 2009-11-05 Created: 2009-10-28 Last updated: 2009-10-29Bibliographically approved

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