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

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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.