PEP regulates flower reproductive organ identity and determinacy.
A) Scanning Electron Microscopy micrograph (SEM) of a post-anthesis wild-type flower. The different parts of the pistil have been artificially colored: stigma (yellow), style (purple), ovary (green), gynophore (g, orange). pt, petal; st, stamen; s, sepal. B-F) Post-anthesis flowers of different mutant backgrounds. Some outer organs were removed to better show petaloid stamens in the third whorl (arrows). G-I) SEM micrographs. Petal (G) and anther (I) adaxial surface in wild-type. Adaxial side in third whorl organs in hua1 hua2 pep/+ flowers (I). J) SEM apical portion of wild-type pistil. K-N) Top portion (SEM micrographs) of gynoecia/fruits from different mutant combinations. O) hua1 hua2 pep/+ pistils developed extra valves (asterisks) topped by white tissue that resembled that of sepal tips (white arrows). No style and very rudimentary stigmatic tissue were observed (yellow arrow). P) Medial view (SEM micrograph) of stage 17 wild-type fruit (according to ). Q) Abaxial surface of hua1 hua2 pep/+ gynoecia. R) Abaxial side of a wild-type sepal. S) A hua1 pep flower after outer organ abscission. Sepaloid carpels (white arrows) formed the fourth whorl that developed on a long gynophore. Similar structures were seen developing inside the sepaloid gynoecia which also contained rudiments of stigmatic tissue (yellow arrow) and further additional floral organs (red arrow). T) hua1 hua2 pep/+ fourth whorl. U-W) hen4 hua1 hua2/+ pep/+ flowers. Fourth whorl organs were removed to observe inner flowers (U, V). X) mRNA expression levels of AG in the wild type (WT) and diverse hua-pep mutant backgrounds, monitored by quantitative RT-PCR (qPCR). Error bars, standard deviation (SD). Asterisks indicate statistically significant differences from hua1 hua2 plants (*P < 0.05). On panels (K, L, N, Q) and (R) some giant cells appear false-colored. Scale bars: 1 mm (B, C, D, E, F, S, T, U, V, W), 500 μm (O), 200 μm (A), 100 μm (J, K, L, M, N, P, Q, R) and 10 μm (G, H, I). nc, nectaries; r, replum; sy, style; v, valve.