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Photosynthesis and temperature, with particular reference to effects on quantum yield
Symposia of the Society for Experimental Biology
|January 1, 1988
Summary
Temperature stress, particularly chilling, significantly reduces the quantum yield (phi) of photosynthesis in maize, impacting light-limited processes more than light-saturated rates. Recovery of phi is slow, with implications for overall crop productivity.
Area of Science:
- Plant Physiology
- Photosynthesis Research
- Molecular Biology
Background:
- Temperature significantly affects photosynthesis, with a focus on light-saturated rates.
- Quantum yield (phi) of photosynthesis, a measure of light-limited photosynthesis, is often considered temperature-insensitive.
- Photoinhibition, damage to the photosynthetic apparatus at temperature extremes, consistently reduces phi.
Purpose of the Study:
- To investigate the impact of chilling-induced photoinhibition on both quantum yield (phi) and light-saturated rates (Asat) of photosynthesis in maize.
- To analyze the recovery dynamics of phi and Asat following chilling stress.
- To evaluate the relative importance of changes in phi versus Asat for canopy photosynthesis under varying light conditions.
Main Methods:
- Analysis of CO2 uptake recovery in maize leaves after chilling.
- Modeling of maize crop photosynthesis using canopy models.
- Biochemical analysis of thylakoid membranes, including atrazine binding and polypeptide identification.
- Examination of photosystem II (PSII) and associated complexes under stress.
Main Results:
- Chilling-dependent photoinhibition in maize reduces both phi and Asat.
- While Asat recovers within hours, phi recovery may take days.
- Canopy models indicate that changes in phi are more critical for average summer day photosynthesis than changes in Asat.
- Chilling reduces PSII quantum yield and whole-chain electron transport, linked to damage of the QB protein.
- A 31 kDa polypeptide accumulates in thylakoids, potentially affecting LHCII energetics and reducing phi.
Conclusions:
- Temperature-induced decreases in quantum yield (phi) are a significant factor in plant stress responses.
- The slow recovery of phi highlights its vulnerability and importance in photosynthetic efficiency.
- Further research into thylakoid membrane factors influencing phi is warranted to understand stress impacts on photosynthesis.