Figure 1.

Thermomorphogenic response requires both PIF4 and PIF7 for hypocotyl and petiole elongation in Arabidopsis. (a) Hypocotyl elongation of wild‐type (Col‐0) and pif mutants grown in long days (LDs) at 21°C for 4 d then either kept at 21°C or transferred to 28°C (at ZT2 on day 5) for three additional days. Elongation during the last 3 d is indicated. Different letters indicate significant difference (two‐way ANOVA with Tukey's HSD test, P < 0.05, n > 25). (b) High‐resolution growth analysis of Col‐0, pif4‐101, and pif7‐1 seedlings. Hypocotyl elongation from LD‐grown seedlings (21°C) was measured from time‐lapse images with indicated intervals starting from ZT0 on day 5. The red dashed line indicates start of 28°C treatment at ZT2 on day 6. The grey zone represents the dark period. Data represent means ± 2 SE; n > 8. (c) Petiole lengths (leaf 3) of Col‐0 and pif mutants grown in LD at 21°C for 15 d then either kept at 21°C or transferred to 28°C for three additional days. Different letters indicate significant difference (two‐way ANOVA with Tukey's HSD test, P < 0.05, n = 10). For (a) and (c) the horizontal bar represents the median, boxes extend from the 25^th to the 75^th percentile, while whiskers extend to 1.5 times the interquartile range of the lower and upper quartiles, respectively, outliers are indicated with circles.