The appearance of photosynthetic proteins in developing maize leaves

The appearance of photosynthetic proteins was directly measured in developing maize (Zea mays L.) leaves. Third leaves of 10-14-d-old seedlings were dissected into six successive sections from the basal meristem to the tip of the leaf. The membrane and soluble proteins were separated by polyacrylamide gel electrophoresis and then transferred onto cyanogen bromide paper. After transfer of membrane proteins the paper was reacted with antisera raised against the light-harvesting chlorophyll a/b protein of photosystem II, the chlorophyll a-binding protein of reaction center P-700 of photosystem I and the α-subunit of chloroplast-coupling factor 1. The blots of soluble proteins were reacted with antisera raised against the electron-transport proteins plastocyanin and Fe-NADP reductase (EC 1.6.7.1), the carbon-fixing enzymes ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) and phosphoenolpyruvate carboxylase (EC 4.1.1.31), as well as pyruvate orthophosphate dikinase (EC 2.7.9.1). The schedule of appearance of proteins shows that the light-harvesting and ATP-generating proteins are present in the most immature segments at the leaf base and accumulate rapidly as the cells mature. The carbon-reducing enzymes, however, appear only in tissue that has differentiated into mesophyll and bundle-sheath cells.