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Hydrogen-peroxide-mediated catalase gene expression in response to wounding
1Department of Genetics, North Carolina State University, Raleigh, NC 27695-7614, USA.
Free Radical Biology & Medicine
|July 13, 2000
Summary
Wounding upregulates catalase (Cat) gene expression in maize embryos, potentially via jasmonic acid (JA). In leaves, Cat1 and Cat3 are induced by wounding, independent of JA and abscisic acid (ABA), possibly involving reactive oxygen species (ROS).
Area of Science:
- Plant Molecular Biology
- Plant Physiology
- Biochemistry
Background:
- Catalase (Cat) enzymes are crucial for managing reactive oxygen species (ROS) in plants.
- Wounding triggers complex defense responses in plants, involving various signaling pathways.
- Understanding gene regulation under stress conditions is vital for crop improvement.
Purpose of the Study:
- To investigate the effect of wounding on catalase gene expression in maize embryos and leaves.
- To explore the roles of jasmonic acid (JA) and abscisic acid (ABA) in wound-induced catalase expression.
- To identify signaling molecules and regulatory elements involved in the plant's antioxidant response to wounding.
Main Methods:
- Quantitative analysis of Cat gene transcript levels in response to wounding and hormone treatments (JA, ABA).
- Genetic analysis using ABA-deficient mutants to assess ABA's role in wound response.
- Reporter gene assays (Gus) to identify cis-regulatory elements in the Cat1 promoter.
Main Results:
- All three maize Cat genes (Cat1, Cat2, Cat3) were upregulated by wounding in immature embryos, with JA potentially mediating this response.
- In young leaves, wounding induced Cat1 and Cat3 expression, but not Cat2. This induction was independent of JA and ABA.
- Wounding increased endogenous hydrogen peroxide (H2O2) levels in leaves, suggesting a role for ROS in the antioxidant response.
- The Cat1 promoter contains a wounding-responsive element that overlaps with an ABA-responsive element (ABRE/G-box).
Conclusions:
- Wounding elicits distinct catalase gene expression patterns in maize embryos and leaves.
- Jasmonic acid (JA) may be involved in the wound response of catalase genes in embryos, while abscisic acid (ABA) does not mediate this response in leaves.
- Reactive oxygen species (ROS), particularly H2O2, likely play a role in the wound-induced antioxidant defense in maize leaves, potentially acting as signaling molecules.