Abstract
Chlorophylls are the main light-harvesting pigments that bring photons to reaction centers. It is, however, not yet entirely clear how the light-harvesting complexes are formed and function. The pcb2 mutant is deficient in divinyl protochlorophyllide 8-vinyl reductase and thus accumulates divinyl chlorophylls instead of chlorophylls. To obtain more information about the role of the chlorophylls in photosynthesis, we investigated the photosynthetic activity and the formation of the photosynthetic components in the pcb2 mutant. Chlorophyll fluorescence analysis showed that the photosynthetic electron transport system of photosystem II, especially reaction center, did not function adequately in the pcb2 mutant. Green Gel analysis showed that a component of the photosystem had been disturbed. Electron microscopic analysis showed that the chloroplasts of pcb2 mesophyll cells lacked distinctive grana stacks. We discuss the effect of divinyl chlorophylls on photosynthesis and the formation of grana stacks.
