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Photosynthesis and photorespiration in algae.
N D Lloyd1, D T Canvin, D A Culver
1Department of Biology, Queen's University, Kingston, Ontario K7L 3N6.
Plant Physiology
|May 1, 1977
Summary
This study investigated photorespiration in freshwater and marine algae. Results indicate that algae do not exhibit photorespiration, challenging previous scientific proposals.
Area of Science:
- Plant Physiology
- Algal Biology
- Biochemistry
Background:
- Photorespiration is a light-dependent process in plants that can reduce photosynthetic efficiency.
- Previous research suggested that photorespiration might occur in certain algal species.
Purpose of the Study:
- To determine if photorespiration occurs in freshwater and marine algae.
- To investigate the CO(2) exchange mechanisms in algae under varying oxygen concentrations.
Main Methods:
- Algae were cultured and positioned as thin layers on filter paper.
- Carbon dioxide (CO(2)) exchange was measured using an open gas exchange system.
- Uptake of carbon-14 dioxide ((14)CO(2)) and carbon-12 dioxide ((12)CO(2)) was compared under different oxygen levels.
Main Results:
- No significant difference in (14)CO(2) and (12)CO(2) uptake was observed between 21% and 1% O(2).
- Apparent photosynthesis remained constant across 2%, 21%, and 50% O(2) conditions.
- CO(2) evolution in light was lower than in darkness, and compensation points were below 10 mul l(-1).
Conclusions:
- The observed gas exchange patterns are inconsistent with the occurrence of photorespiration in the studied algae.
- These findings suggest that freshwater and marine algae may possess mechanisms to avoid or minimize photorespiration.