Fig. 5: Low temperature suppresses PIF4s function at both mRNA and protein levels.

Bud set scores of WT and PIF4a-YFP OE3 grafted plants during SD-induced growth cessation at 21 °C (a) and 15 °C (b). Representative pictures of the shoot apices are shown in the right panel. The dotted line marked bud set score 2, which indicates the stage of growth cessation²⁶. Pictures were taken when the bud set score of WT plants reached stage 2. c Diurnal relative gene expression of PIF4a in leaves of WT and PHYBRNAi-12 trees grown for 40 days at 21 °C and 15 °C. d Western blot analysis of PIF4a-YFP fusion protein in PIF4a-YFP OE3 plants at 21 °C and 15 °C using an anti-GFP antibody to detect PIF4a-YFP and an anti-RPN6 antibody as a loading control. Leaf samples were taken at ZT0, 4, 8, 12 (shown in the upper panel), and ZT16, 18, 21, and 24 (shown in the lower panel). n.b. indicates a non-specific band. e Quantification of PIF4a-YFP fusion protein from western blots. f Quantitative analysis of western blots of PHYB2-GFP fusion protein in PHYB2-GFP OE6 soil-grown plants under LD conditions at 21 °C and 15 °C. Leaf samples were collected at ZT0, 4, 8, 12, 16, 18, 21, and 24. The original western blots are shown in Supplementary Fig. 5c. Data are presented as mean ± SEM (n = 10 for a, b; n = 3 for c, e, f). Fisher’s LSD post hoc tests (two-sided, uncorrected for multiple comparisons) were performed at all time points following ANOVA. The statistically significant differences are indicated by non-matching letters in (c) (p < 0.05). Asterisks in a, b, e, f indicate the levels of statistical significance, *p < 0.05, ** p < 0.01. See also Supplementary Fig. 5 and Supplementary Table 1. Source data are provided as a Source Data file.