Reduction in Carbonic Anhydrase Activity in Zinc Deficient Leaves of Phaseolus vulgaris L.1

Abstract

The effect of zinc deficiency on plant growth and levels of carbonic anhydrase, ribulose diphosphate carboxylase, glycolic oxidase, and malic dehydrogenase was measured in two varieties of Phaseolus vulgaris L. Varieties ‘Saginaw’ and ‘Sanilac’ were grown in nutrient solution in a growth chamber at 0.005, 0.05, and 0.2 ppm zinc. Both varieties showed a similar increase in dry weight production after 4½ weeks of growth with increasing zinc concentrations. Enzyme, chlorophyll, and zinc analyses were made on the first, third, and fifth trifoliate leaf from the bottom of the plants. The level of carbonic anhydrase per unit leaf area was dramatically decreased in either variety at 0.005 and 0.05 ppm zinc when compared to 0.2 ppm zinc. The most severe reduction of carbonic anhydrase and zinc in the leaves was in the third and fifth trifoliate leaf. A decrease in growth with the lower levels of zinc was paralleled by a decrease in carbonic anhydrase activity and zinc levels in the younger trifoliate leaves. Zinc deficiency in the two varieties had little effect on the levels of ribulose 1,5‐diphosphate carboxylase, glycolic oxidase, or mallc dehydrogenase.