Measurement of the Leakage of CO2 from Bundle-Sheath Cells of Leaves during C4 Photosynthesis

摘要: During C4 photosynthesis, CO2 is released in bundle-sheath cells by decarboxylation of acids and then refixed via ribulose-1,5-bisphosphate carboxylase. In this study we examined the efficiency process determining proportion that diffuses back to mesophyll instead being refixed. This leak was assessed amount 14CO2 from leaves during a chase high [12CO2] following 70-s pulse 14CO2. A computer-based analysis time-course curve for release indicated first-order provided an estimate initial velocity leaves. From value net rate photosynthesis determined fixed pulse, (expressed as percentage production acids) could be deduced. For nine species Gramineae representing different subgroups plants two NAD-malic enzyme-type dicotyledonous species, ranged between 8 14%. However, very rates (averaging about 27%) were recorded NADP-malic Flaveria. The results are discussed terms observed quantum yields.