Sulfite Sensitivity of Light Modulation of Chloroplast Enzyme Activity is Controlled by a Cytoplasmic Gene

Effects of Arsenite, Sulfite, and Sulfate on Photosynthetic Carbon Metabolism in Isolated Pea (Pisum sativum L., cv Little Marvel) Chloroplasts

“…Long-term exposure of the light modulation system to SO2 (= sulfite) might, however, affect light activation of the enzymes of photosynthetic CO2 fixation. In experiments in this laboratory with two Pisum varieties chosen for differences in SO2 tolerance, differences in photosynthetic sensitivity paralleled differences in the sensitivity of the light modulation system (21). It seems likely that the relative importance of the various factors involved in S02-sensitivity differs between species and between cultivars.…”

“…In chloroplasts sulfite (at pH 8.2: 9.2% HSO3-and 90.8% S032-) and effectors induced by SO2 fumigation can attack reactions of photosynthetic electron transport (7, 26), photophosphorylation (5, 27), and the reductive pentose phosphate pathway (10,14,17,24,29,(31)(32)(33). Light modulation of stromal enzyme activity in the chloroplast is known to be sulfite sensitive (3,20,21).…”

“…In chloroplasts sulfite (at pH 8.2: 9.2% HSO3-and 90.8% S032-) and effectors induced by SO2 fumigation can attack reactions of photosynthetic electron transport (7, 26), photophosphorylation (5, 27), and the reductive pentose phosphate pathway (10,14,17,24,29,(31)(32)(33). Light modulation of stromal enzyme activity in the chloroplast is known to be sulfite sensitive (3,20,21).In previous experiments involving '4C02 fixation in intact chloroplasts the RPP3 pathway intermediates were only partially resolved (16). To verify the reported SO2 effects and to determine their significance in situ, we have examined the effect of sulfite on the "4CO2 fixation pattern and the distribution of '4C-labeled metabolites between chloroplasts and the incubation medium during photosynthetic induction.…”