Role of micronutrient elements in the metabolism of higher plants. I. Changes in oxidative enzyme constitution of tomato leaves deficient in micronutrient elements

Cell-free extracts of tomato leaves from plants grown on media individually deficient in each of the micronutrient elements showed marked changes in enzymatic constitution. Each deficiency caused an alteration in the over-all enzyme pattern which was characteristic of the micronutrient element in question. The metallo-enzymes such as polyphenol oxidase, ascorbic acid oxidase, and peroxidase lost approximately half their activity in plants deficient in the specific metal concerned. In the cases of all other metal deficiencies, however, polyphenol oxidase and peroxidase were elevated in concentration at least two to six times that of the control. Ascorbic acid oxidase was doubled in zinc- and manganese-deficient material. Glycolic acid dehydrogenase and lactic acid dehydrogenase showed smaller parallel rises averaging a one and a half fold increase in content in zinc- and manganese-deficient plants. Reduced diphosphopyridine nucleotide diaphorase was doubled by copper and manganese deficiencies and was increased to almost one and a half fold by zinc deficiency. Endogenous oxygen uptake in boron-deficient, copper-deficient, and manganese-deficient leaf homogenates was increased, and almost lacking in molybdenum-deficient material.