Figure 3.

Characteristics of pp2a-b′γ, cpr5, the pp2a-b′γ cpr5 double mutant, and wild-type plants. A, Clustering of genes differentially expressed between pp2a-b′γ mutant and wild-type (WT Col) plants under normal growth light conditions (GL; 130 μmol photons m⁻² s⁻¹) or after growth under high light (HL; 800 μmol photons m⁻² s⁻¹). Genes that showed statistically significant (Student’s t test; P < 0.05) differences in expression of at least 1.5-fold under either GL or HL are presented. The Venn diagram demonstrates the number of up-regulated genes in pp2a-b′γ mutant plants under GL and HL. B, Visual phenotypes and accumulation of H₂O₂ in pp2a-b′γ, cpr5, and the pp2a-b′γ cpr5 double mutant after a 4-week growth period under GL and HL. For visualization of H₂O₂, rosettes were floated on 0.1% DAB under GL conditions for 2 h. The accumulation of H₂O₂ is visualized as a brown precipitate on the leaves. Projections of sequential confocal microscopy images of Hoechst-stained trichomes (T) of the wild type, pp2a-b′γ, cpr5, and the pp2a-b′γ cpr5 double mutant are shown between the photographs. Bar = 100 μm. C, Sensitivity to MV-induced photooxidative stress. Plants were sprayed with 50 μm MV and illuminated under 130 μmol photons m⁻² s⁻¹ for 6 h prior to measurement of ion leakage from the leaves. Control samples were illuminated under normal GL conditions. The values are means ± sd (n = 9). ** P < 0.05 by Student’s t test. D, Levels of SA and JA in pp2a-b′γ, cpr5, and the pp2a-b′γ cpr5 double mutant after a 4-week growth period under GL. *** P < 0.005 by Student’s t test. FW, Fresh weight.