Extended Data Fig. 6: Phosphorylation at T282 of FD is essential for its interaction with 14-3-3 proteins in vivo and in vitro.

a, The phosphopeptide of FD was analyzed by LC-MS/MS. The phosphorylation of T282 is revealed in MS2 spectra. The observed fragment ions are labeled on the spectrum and peptide sequence (phosphorylated T282 is marked in orange). b, Flowering time (total leaf number, TLN) of transgenic fd-3 mutant plants carrying gFD::3HA-3Flag-FD^WT, gFD::3HA-3Flag-FD^T282E or gFD::3HA-3Flag-FD^T282A in LDs. Different letters represent significant differences among genotypes (P < 0.05), using one-way ANOVA followed by Tukey’s pairwise multiple comparison, P = 1.11 * 10⁻¹⁶. c, Modeled structure of the FD^SAP–GRF7 complex with phosphorylation, wild type (WT) or mutations on residue T282 (c.1–c.4). d–f, Volcano plots showing differential protein abundance based on label-free quantification. The log₂-transformed fold change between genotypes FD^WT to Col-0, FD^T282A to Col-0 or FD^WT to FD^T282A is plotted against the -log₁₀ of the adjusted p-value. Statistical significance was assessed using a two-sided t-test with permutation-based false discovery rate (FDR) correction (AdaPT method). Proteins with log₂ (fold change) > 1 and FDR-adjusted p < 0.05 are highlighted in distinct colors as significant outliers. g–j, Size-exclusion chromatography and gel analysis of GRF7 with MBP-FD^{2–285 (T282E)} (g, h) or MBP-FD^{2–285 (T282A)} (i, j). Data are representative of two independent experiments.