Fig. 4
Representative photographs of the ovule development after allogamy and interspecific crossing. Allogamy (A–H); interspecific crossing (I–L). D. fuchsii (A,B,E,F); D. majalis (G,H); D. maculata (C, D). (A) 24 HAP, archespore cell. (B–C) 48 HAP, megaspore mother cell at prophase I. (D) 24 HAP, metaphase I, losing bivalent/chromosome marked by arrowhead. (E) 5 DAP, the dyad stage. (F) 5 DAP, the functional megaspore stage; the remnants of degenerated megaspores are marked by a star. (G–H) 5 DAP, mature FG with an egg cell (G), two synergid cells and two polar nuclei (H). (I) ♀ D. fuchsii × D. incarnata ♂ 24 HAP, metaphase I. (J–K) ♀ D. incarnata × D. majalis ♂ 24 HAP, the dyad stage. (L) ♀ D. incarnata × D. majalis ♂ 24 HAP, the functional megaspore stage. Similar ovule developmental stages were observed for all tested species. mmc-megaspore mother cell; ii-inner integument; oi-outer integument; chd-chalazal cell of the dyad; md-micropylar cell of the dyad; ; FM-functional megaspore; ec-egg cell; pn-polar nucleus. Bar = 20 µm for all images.
