Fig. 1: BR are necessary for endosperm development.

a–d Microscopic photos of WT unfertilized ovule (a), PRC2 mutant seeds (b, c), and an auxin-induced autonomous seed (d). Scale bars, 50 μm. This experiment was repeated three times with similar results. e, f Quantification of endosperm nuclei and size in seeds of the genotypes indicated in panels (b–d). Error bars represent standard deviation. The letters on top indicate significance of differences by one-way analysis of variance (ANOVA). The number below each sample indicate number of seeds analyzed. g, h Simplified BR biosynthesis (g) and signaling (h) pathways. i Endosperm nuclei number 2 days after pollination (2 DAP) for BR mutants and respective WT. Error bars represent standard deviation. The letters on top indicate significance of differences by one-way ANOVA. The number below each sample indicate number of seeds analyzed. j, k 2 DAP seeds of WT (b) and det2-1^−/− (c). Scale bars, 50 μm. These experiments were repeated a minimum of three times with similar results. l Percentage of ovules developing autonomous endosperm after the application of exogenous auxin (mock) or auxin in combination with different concentrations of epi-brassinolide. m Autonomous endosperm development in BR and PRC2 double mutants, and respective single mutants, at 5 DAE. The values on top indicate the number of ovules analyzed. Significance of difference was determined by one-way chi-squared test. ****p < 0.0001, ***p < 0.001, **p < 0.01 and *p < 0.05.