Initiation of Sulfate Activation: A Variation in C 4 Photosynthesis Plants

Abstract
In leaves of plants with C4 photosynthesis, sulfur assimilation is initiated in bundle sheath cells whereas carbon and nitrogen assimilation are initiated in mesophyll cells. The activation of sulfate by adenosine triphosphate sulfurylase in leaves of C4 plants occurs in chloroplasts of bundle sheath cells and is effected by two isozymes of approximately equal activities that accounted for 95 to 100 percent of the total leaf activity.