Fig. 3.

High light inhibits phototropism in a phot1- and S299-dependent manner. a Phototropic curvature of Col-0 seedlings treated with 10, 100, or 600 µmol m⁻² s⁻¹ unilateral blue light for 3 h prior to measurements. n = 68−97. b Phototropic curvature of pks4 PKS4-WT-3, pks4 S299A-2, and pks4 S299D-1 seedlings treated with 100 or 600 µmol m⁻² s⁻¹ unilateral blue light for 6 h prior to measurements. n = 25−43. c Western blot probed with anti-PKS4 antibodies from long-day (LD) grown Col-0, phot1, phot2, and phot1phot2 samples exposed to 600 µmol m⁻² s⁻¹ blue light for 0, 2, 10, 30, or 60 min. Samples from etiolated Col-0 seedlings are used as a control. Asterisks indicate unspecific band. d Phototropic curvature of Col-0, phot1, phot2, and phot1phot2 seedlings treated with 100 or 600 µmol m⁻² s⁻¹ unilateral blue light for 6 h prior to measurements. n = 29−69. e Phototropic curvature of seedlings of Col-0, pks4 PKS4-WT-3, pks4 S299A-2, phot1, and phot2 placed in a greenhouse at ZT4, blue light was ~250 µmol m⁻² s⁻¹. Phototropic bending was measured after 1 h and 45 min. n = 109–154. Seedlings were grown for 3 days in a 16–8 h day−night cycle, the experiment started 2 h after dawn (ZT2) except for panel (e). Data represent means. Error bars correspond to 2× standard error. Means with same letter are not significantly different (p > 0.05, one-way ANOVA test for (a) and (e), two-way ANOVA for (b) and (d))