Figure 4.

HY5 and TZP coordinately regulate FR light signaling. A, Phenotypes of 4-day-old Col, tzp-1, tzp-2, hy5, tzp-1 hy5, tzp-2 hy5, HA-HY5#3, HA-HY5#3 tzp-1, and HA-HY5#3 tzp-2 seedlings grown in FR light (10 μmol m⁻² s⁻¹). Scale bar = 1 mm. B, Hypocotyl lengths of the respective seedlings shown in (A). Data are means ± sd from 15 seedlings. **P < 0.01 and ***P < 0.001 (Student’s t test; Supplemental Data Set S3) for the indicated pair of samples. C, Cluster analysis of genes whose expression was changed in 4-day-old FR-grown (10 μmol m⁻² s⁻¹) hy5, tzp-2, and tzp-2 hy5 seedlings compared with those in Col. The bar represents the log₂ of the ratio. D, Venn diagram showing the numbers and overlaps of genes whose expression was changed in hy5, tzp-2, and tzp-2 hy5 seedlings compared with those in Col. E, RT-qPCR data showing the expression levels of TZP, ELIP2, and PRP2 in Col, tzp-2, hy5, tzp-2 hy5 mutant seedlings grown under different rates of FR light for 4 days. Error bars represent SE of three different pools of seedlings. Data are normalized to TUBULIN3. Different letters represent significant differences by one-way ANOVA with Duncan’s post hoc test (P < 0.05; Supplemental Data Set S3). F, RT-qPCR assays showing the relative expression of TZP, ELIP2, and PRP2 in 4-day-old Col, hy5, tzp-2, and tzp-2 hy5 mutant seedlings grown in the dark, and then transferred to FR light (50 μmol m⁻² s⁻¹) for 1 h and 6 h. Error bars represent se of three different pools of seedlings. Data are normalized to TUBULIN3. Different letters represent significant differences by one-way ANOVA with Tukey’s post hoc test (P < 0.05; Supplemental Data Set S3).