Fig. 4.

Shade-induced hypocotyl growth requires sugar transport. Hypocotyl length of sucrose transport mutants suc2 (A) and sweet11 sweet12 (B), grown in long days. Length was measured after 5 d of growth in high R:FR and a subsequent 3 d in high (light gray) or low R:FR (dark gray). Seedlings were transferred to medium supplemented with 1% sucrose or the molar equivalent in sorbitol after 5 d. Data represent means ± 2 SE; n > 20. Different letters indicate significant difference after 8 d. Statistics (two-way ANOVA, P < 0.05) were split per genotype due to significant interaction effects. (C) High-resolution growth analysis of Col-0, suc2, and sav3 seedlings around the start of low-R:FR treatment. Hypocotyl length from long-day grown seedlings was measured from time-lapse images with 2-h intervals starting from ZT2 after 4 d of growth. The next day, images were taken at 30-min intervals after the start of low-R:FR treatment at ZT2. Relative hypocotyl length was calculated by dividing hypocotyl length at each time point by its length at the start of measurements. The black bar in the x axis represents the dark period. Data represent means ± 2 SE; n > 30.