Porphyrinogenesis in maize as affected by bidentate chelators of iron

Etiolated maize (Zea mays L. cv. Senesca Chief hybrid sweet) leaves incubated in darkness with bidentate chelators of iron are shown to accumulate protoporphyrin and Mg‐porphyrins to concentrations higher than controls. The accumulation of 5‐aminolevulinic acid in vivo is inhibited by chelators. The heme content of the chelator treated tissues was not decreased relative to the controls. The presence of bidentate chelators inhibited the metabolism of porphobilinogen in crude extracts of maize. The porphyrinogenic effect of chelators in maize is different than that reported for bean. It is suggested that enhancement of porphyrin accumulation in maize in the presence of bidentate chelators of iron is the result of an increased stability of endogenous porphobilinogen.