Limiting Factors in Photosynthesis: III. Effects of Iron Nutrition on the Activities of Three Regulatory Enzymes of Photosynthetic Carbon Metabolism.

When Fe was withheld from sugar beets (Beta vulgaris L. CV F58-44H1), the activities of NADP-glyceraldehyde-3-phosphate dehydrogenase, fructose 1,6-bisphosphatase, and ribulose 5-phosphate kinase were not diminished, while chlorophyll per area was decreased by 75%. On resupplying Fe, chlorophyll per area increased to control levels within 5 days, whereas the activities of the three enzymes remained approximately constant. These results support the view advanced earlier (Terry 1980 Plant Physiol 65: 114-120) that the photosynthetic effects of Fe deprivation are mediated by changes in the lamellar components of chloroplasts and not by changes in stromal enzymes involved in photosynthetic carbon reduction.