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Reactive nitrogen species-dependent effects on soybean chloroplasts
Susana Puntarulo1, Sebastián Jasid, Marcela Simontacchi
1Physical Chemistry-PRALIB; School of Pharmacy and Biochemistry; University of Buenos Aires; Buenos Aires, Argentina.
Plant Signaling & Behavior
|August 26, 2009
Summary
Soybean chloroplasts generate nitric oxide (NO) from nitrite and L-arginine. While NO can have antioxidant effects, reactive nitrogen species like peroxynitrite can cause oxidative damage to chloroplasts.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Nitric oxide (NO) is a signaling molecule in plants.
- The role of NO in chloroplasts is not fully understood.
- Soybean chloroplasts are a key site for photosynthesis and cellular processes.
Purpose of the Study:
- To investigate nitric oxide (NO) generation in soybean chloroplasts.
- To determine the substrates and enzymes involved in NO production.
- To assess the impact of NO and reactive nitrogen species on chloroplast function.
Main Methods:
- Electron paramagnetic resonance (EPR) spin-trapping technique was used to detect NO.
- Enzymatic assays were performed using nitrite and L-arginine as substrates.
- Chloroplasts were exposed to NO donors and peroxynitrite to study oxidative effects.
- Western blotting was employed to assess protein oxidation.
Main Results:
- Soybean chloroplasts produced NO from both nitrite and L-arginine.
- NO production was inhibited by NOS inhibitors (L-NAME, L-NNA).
- Exposure to a NO donor decreased ascorbyl radical content and ascorbate peroxidase activity.
- Peroxynitrite increased lipid-derived radicals and protein oxidation (carbonyl content).
Conclusions:
- Nitric oxide (NO) is an endogenous metabolite in soybean chloroplasts.
- Reactive nitrogen species can exert both antioxidant and prooxidant effects on chloroplasts.
- Understanding NO's role is crucial for plant stress response and photosynthesis.
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