Revisiting the Temperature Dependence of the Photorespiratory CO(2) Compensation Point (Γ*).

Improved Laisk-FvCB analysis of sunflower leaves across 3.9–42.0°C yields a revised photorespiratory CO2 compensation point Γ*(T) with Γ*(25)=43.4 μmol mol−1.

• Why it matters: Accurate Γ* and light CO2 release estimates are needed to balance Rubisco carboxylation versus oxygenation and to parameterise biochemical photosynthesis models.
• What they did: Gas exchange was measured over 3.9–42.0°C, and the improved Laisk-FvCB framework constrained the nonlinear A_net–c_c response across multiple sub-saturating irradiance levels.
• The result: The mechanistically constrained approach produced physiologically meaningful Γ*(T) and reduced artefacts from linear Laisk extrapolation, deriving an Arrhenius-type Γ*(T) with apparent activation energy 27.7 kJ mol−1.

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