Fig. 6: Glutathione reductase deletion protects against H₂O₂-induced NADP oxidation in plants.

a Cartoon showing two possible pathways by which electrons from NADPH can be transferred to H₂O₂ in the plant cytosol, AsA ascorbic acid, APX ascorbate peroxidase, DHAR dihydroascorbate reductase, GR glutathione reductase, TPX thiol peroxidase, TRX thioredoxin. Created with BioRender.com. Response of a cytosolic NAPstar4.3 probe to exogenous H₂O₂ at the indicated concentrations in wild-type (Col-0) plants (b), gr1 (c), ntr a/b (d) plants, and the control construct NAPstarC in wild-type plants (e) (n = 6, except for NAPstar4.3 with 10 mM H₂O₂ in ntr a/b where n = 5, leaf discs from 6 (or 5) individual plants). f, Box and whisker plot, derived from the datasets presented in b–d, showing the change in TS/mC before and after treatment with 20 mM H₂O₂. Boxes show the interquartile range, with the middle line defining the median. ‘X’, represents the mean values. Whiskers show the minimum and maximum values, excluding outliers. Dots indicate outlier values, which are defined as being 1.5 times the interquartile range above and below the third and first quartile respectively. P-values are derived from a one-sided ANOVA test. In all panels, data are presented as mean ± s.d. normalised to the average value before addition of H₂O₂.