Figure 1. The sak1 mutant is defective in singlet oxygen acclimation.
(A) Acclimation phenotype of WT and sak1. The cells were pretreated in the dark (−) or under light (+) in the presence of rose bengal (RB), which requires light for generation of 1O2. Pretreatment was followed by a subsequent higher concentration of RB (Challenge) as indicated under light. (B) Cells grown in low light were either kept in low light (−) or transferred to high light (+) for an hour before challenge in the light with increasing RB concentrations. (C) Fv/Fm values were measured after each time point indicated. Pretreatment (PreT) with 0.5 μM RB was applied for 30 min with (+PreT) or without (−PreT) light. After the pretreatment, RB was added to both dark and light samples to a final concentration of 3.75 μM RB (challenge), and Fv/Fm was measured for 90 min at 30 min intervals (total 120 min). First arrow: addition of pretreatment; second arrow: addition of challenge. (D) sak1 has wild-type sensitivity to other photo-oxidative stresses. Serial dilutions of WT and sak1 were spotted onto minimal (HS) plates at the indicated light intensity or on TAP plates containing the indicated inhibitor. DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea; low light (LL), 80 µmol photons m−2 s−1; high light (HL), 450 µmol photons m−2 s−1. (E) Gene expression of a known 1O2-responsive gene, GPX5, is induced during acclimation, while two genes associated with H2O2 response, APX1 and CAT1, are not. WT cells were mock-pretreated without RB (white bars) or pretreated with RB in the light (black bars).
Figure 1—figure supplement 1. Pretreatment with RB does not increase resistance to high light or norflurazon in cells grown on plates.
