Mesophyll conductance (gm) and chloroplast CO2 concentrations (Cc)
Leaf g m to CO2 and C c were calculated from the combined gas exchange and other parameters (Harley et al., 1992). The g m in VC was 0.05 mol CO2 m–2 s–1bar–1 and C c was substantially lower than C i (173 μmol CO2mol–1 at 319 μmol CO2mol–1). In the two transgenics,g m increased to 0.069 or 0.073 mol CO2 m–2 s–1bar–1 which led to significantly higherC c (8% - 10%) than in the VC. Although we had problems in accurately measuring g m andC c because of the small size ofArabidopsis leaves, yet, we consistently observed small increases in C c for FbβCA3 overexpressors over the VC.