The C4 Pathway and Its Regulation

Abstract

Nearly a century ago botanists first examined and described an arrangement of green leaf cells known today as Kranz leaf anatomy with its characteristic green mesophyll and bundle sheath cells. Research with the last decade has revealed this "undiscovered division of labour" between mesophyll and bundle sheath cells and chloroplasts. The physical localization of chloroplasts in these adjacent leaf cells initially made direct studies difficult and contributed to some controversy about this division of labour. However to understand C4 photosynthesis one must have a clear picture of Kranz leaf anatomy because two green cell types are present in all plants in which C4 photosynthesis has been well documented.