Remizowa Margarita V, Sokoloff Dmitry D
Biological Faculty, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia.
Plants (Basel). 2023 Dec 12;12(24):4138. doi: 10.3390/plants12244138.
The phenomenon of heterochrony, or shifts in the relative timing of ontogenetic events, is important for understanding many aspects of plant evolution, including applied issues such as crop yield. In this paper, we review heterochronic shifts in the evolution of an important floral organ, the carpel. The carpels, being ovule-bearing organs, facilitate fertilisation, seed, and fruit formation. It is the carpel that provides the key character of flowering plants, angiospermy. In many angiosperms, a carpel has two zones: proximal ascidiate and distal plicate. When carpels are free (apocarpous gynoecium), the plicate zone has a ventral slit where carpel margins meet and fuse during ontogeny; the ascidiate zone is sac-like from inception and has no ventral slit. When carpels are united in a syncarpous gynoecium, a synascidiate zone has as many locules as carpels, whereas a symplicate zone is unilocular, at least early in ontogeny. In ontogeny, either the (syn)ascidiate or (sym)plicate zone is first to initiate. The two developmental patterns are called early and late peltation, respectively. In extreme cases, either the (sym)plicate or (syn)ascidiate zone is completely lacking. Here, we discuss the diversity of carpel structure and development in a well-defined clade of angiosperms, the monocotyledons. We conclude that the common ancestor of monocots had carpels with both zones and late peltation. This result was found irrespective of the use of the plastid or nuclear phylogeny. Early peltation generally correlates with ovules belonging to the (syn)ascidiate zone, whereas late peltation is found mostly in monocots with a fertile (sym)plicate zone.
异时性现象，即个体发育事件相对时间的变化，对于理解植物进化的许多方面非常重要，包括作物产量等应用问题。在本文中，我们回顾了重要花器官心皮进化过程中的异时性变化。心皮作为承载胚珠的器官，促进受精、种子和果实的形成。正是心皮赋予了开花植物被子植物的关键特征。在许多被子植物中，心皮有两个区域：近端的凹陷区和远端的褶皱区。当心皮分离（离生雌蕊群）时，褶皱区有一条腹缝线，在心皮发育过程中的心皮边缘在此处相遇并融合；凹陷区从一开始就是囊状的，没有腹缝线。当心皮联合形成合生雌蕊群时，合凹陷区的心皮室数量与心皮数量相同，而合褶皱区至少在发育早期是单室的。在个体发育过程中，要么是（合）凹陷区要么是（合）褶皱区首先开始发育。这两种发育模式分别称为早期和晚期盾状发育。在极端情况下，要么完全没有（合）褶皱区要么完全没有（合）凹陷区。在这里，我们讨论了被子植物一个明确分支单子叶植物中心皮结构和发育的多样性。我们得出结论，单子叶植物的共同祖先的心皮具有这两个区域并且是晚期盾状发育。无论使用质体还是核系统发育树，都得到了这个结果。早期盾状发育通常与属于（合）凹陷区的胚珠相关联，而晚期盾状发育大多出现在具有可育（合）褶皱区的单子叶植物中。
