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. 2016 Jun 10;28(6):1461–1471. doi: 10.1105/tpc.16.00155

Table 2. Estimates of Plasmodesmal Flux between Mesophyll and Bundle Sheath Cells in Leaves of C3 and C4 Species.

Species CO2 Assimilation Rate per Leaf Area (µmol CO2 m−2 s−1) Mean Sb (m2 m−2) CO2 Assimilation Rate per Bundle Sheath Surface Area (µmol CO2 m−2 s−1) CO2 Assimilation Rate per PD (×10−18 mol CO2 s−1) Sucrose Flux per PD (×10−18 mol Sucrose s−1)
Rice, C3 27.1 ± 0.96a 1.1 ± 0.06a 24.7 ± 0.87a 24.7 ± 0.87a 2.1 ± 0.07a
Wheat, C3 35.0 ± 1.48b 1.2 ± 0.17a 29.8 ± 1.26b 11.5 ± 0.49b 1.0 ± 0.04b
S. viridis, C4 29.5 ± 1.50a 1.6 ± 0.04b 18.1 ± 0.92c 1.9 ± 0.10c NA
Maize, C4 38.6 ± 1.14b 2.0 ± 0.08c 19.5 ± 0.58c 2.6 ± 0.08d NA

For the “CO2 Assimilation Rate per PD” column, assuming that in C4 species the minimum flux of C4 acids through the PD needs to be equal to or greater than the CO2 assimilation rate. For C3 species, the numbers indicate the fluxes required if a C4 photosynthetic pathway were installed without anatomical changes. For the “Sucrose Flux per PD” column, assuming sucrose must pass from mesophyll to bundle sheath cells for phloem loading in C3 monocot leaves at a rate in equilibrium with CO2 assimilation rates. Statistical differences according to MATLAB two-sample t test at P value < 0.05 are indicated by letters. Values indicated by the same letter within a column are not statistically different. NA, not applicable.