Abstract
Carbon partitioning of photosynthetic products is thought to be regulated by capacity of sucrose synthesis. To clarify the contribution of cytosolic fructose-1,6-bisphosphatase to the photosynthetic carbon metabolism, we generated transgenic tobacco plants expressing cyanobacterial FBP/SBPase in cytosol (TcFS) and then analyzed photosynthetic characteristics under high CO2 conditions.
In TcFS plants, lateral shoot, leaf number and fresh weight were increased compared with those in the wild-type plants under high CO2 (1200 ppm) conditions. TcFS showed increased photosynthetic activity compared with that in the wild type. The level of hexose of wild type accumulated in upper leaves, while levels of sucrose and starch of TcFS plants accumulated in lower leaves and lateral shoots. These findings suggest that the cytosolic FBPase contributes to efficient conversion of hexose into sucrose, and that the change of the carbon partitioning affects photosynthetic capacity and morphogenesis.
