In this paper, we propose a new model that relates C18OO photosynthetic discrimination ∆18O to carbonic anhydrase (CA) activity, in order to estimate mesophyll conductance (gm) in C3 and C4 plants. Newly ∆18O-derived gm values are usually close but significantly higher (typically 20% and up to 50%) than previous stimates assuming non-limiting CA activity, and relatively robust despite the uncertainty associated with the respiration rate in the light, or the water isotope gradient between mesophyll and bundle sheath cells. An early view version of the paper can be found here.

Schematic representation of photosynthesis in C3 and C4 leaves


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