Plastidic (DTTred-sensitive) G6PDH activities in leaf discs incubated in the dark for 48 h. A, Incubations were conducted either on water (H2O, D), 5 μm Paraquat (Pq, D), 20 mm NO2- (D), or 20 mm NO2- plus 50 mm Glc (NO2- + Glc, D). B, Incubations were conducted either on water (H2O, D), 5 μm Paraquat (Pq, D), 100 mm SO42- (D), or 10 mm SO42- plus 50 mm Glc (SO42- + Glc, D).