Extended Data Fig. 5: Co-expression of OsBBM1 and OsWOX9A using dexamethasone inducible glucocorticoid (GR) induction system.

a. Schematics of OsBBM1-GR and OsWOX9A-GR constructs. (b, c). Phenotype of seeds germinating on ½ MS media mock treated (b), or containing 10μM dexamethasone (c) (no other hormone added), for 2 weeks. From left to right, Wild-type (WT); OsWOX9A-GR; OsBBM1-GR; OsWOX9A-GR + OsBBM1-GR. Scale bars, 1 cm. Wild-type and OsWOX9A-GR germinated normally on dexamethasone (DEX) containing media, while OsBBM1-GR and OsWOX9A-GR + OsBBM1-GR formed calli from scutellum. Red arrowheads indicate shoots emerging from the seeds and white arrowheads point to calli. d. Expression of early embryo marker genes. RT-qPCR log2 fold changes in OSH1 and AMY1 transcripts is shown in OsBBM1-GR calli or OsWOX9A-GR + OsBBM1-GR calli treated for 2 weeks with 10μM dexamethasone. Embryogenic and non-embryogenic calli from scutellum of wild-type seeds were generated by callus induction media as previously described²⁶. The log2 fold change is normalized to wild-type non-embryogenic calli. The height of columns represents mean values of the log2 fold changes, and error bars represent mean values ± SEM, calculated from three independent biological replicates and each data point represents the average of three technical replicates. Two-sided Tukey’s HSD test was used for the statistical analysis, and P values for each comparison are displayed in the graphs. Samples from left to right are: Wild type non-embryogenic calli; wild type embryogenic calli; OsBBM1-GR; OsWOX9A-GR + OsBBM1-GR.