Figure 4.

Plastidic (DTT_red-sensitive) G6PDH activity of leaf discs incubated for 48 h. A, Leaf discs were incubated on water in the light (H₂O, L) or in the dark (H₂O, D), on 5 μm Paraquat in the dark (Pq, D), and in additional presence of 1 mm Chx (Pq + Chx, D). Decreases of plastidic G6PDH activity after 24 h were observed repeatedly but not in all experiments (compare Fig. 5). B, Immunodetection of plastidic G6PDH (P1 isoform) on western blots of leaf discs incubated on either water or Paraquat in the dark for the hours indicated. C, Northern-blot analysis of total RNA (20 μg per lane) isolated from leaf discs incubated on either water or Paraquat in the dark for the hours indicated. The blot was hybridized with radiolabeled cDNA fragments of the P1 isoform (von Schaewen et al., 1995; Wendt et al., 1999) and washed under stringent conditions (three times at 68°C with 0.1× SSC and 0.1% [w/v] SDS). D, Autoradiogram of immunoprecipitated P1 protein after radiolabeling of leaf discs with 500 μCi ³²P in the dark incubated on either water or Paraquat. kD, Molecular mass standards. Numbers above the lanes refer to incubation time in hours.