Investigations of the Role of Iron in Chlorophyll Metabolism I. Effect of Iron Deficiency on Chlorophyll and Heme Content and on the Activities of Certain Enzymes in Leaves

Abstract

The effect of Fe deficiency on the formation of porphyrin compounds in cowpea (Vigna sinensis) leaves was investigated. There was a positive correlation between the concentrations of heme and chlorophyll and the level of Fe in the nutrient solution. Protoporphyrin did not accumulate from endogenous substrates in Fe-deficient or normal tissues. Significantly more protoporphyrin accumulated in Fe-deficient than in normal tissue incubated with [delta]-aminolevulinic acid in the dark. These observations suggest that Fe deficiency results in the limited formation of [delta]-amino-levulinic acid and that this block is one rate-limiting step in chlorophyll synthesis. The activities of catalase and photosynthetic pyridine nucleo-tide reductase in the leaves of cowpea plants are strikingly decreased by a limited Fe supply in the nutrient medium.