Evolutionary study of one-leaf plants (Gesneriaceae)

单叶植物在单叶植物中有分布，在苦瓜科植物中也有分布。它们的植物身体由一个大的子叶组成。它们在整个生活史中从不形成茎或叶，它们在子叶叶片的底部产生花序。本研究旨在基于分子系统发育分析和比较形态发生学来阐明单系的进化。研究材料不仅包括异胚轴的苦瓜亚科，而且还包括同胚轴的金莲亚科。它们是在婆罗洲、马来半岛，包括泰国、马达加斯加、南非和巴西进行的三次植物学考察中收集的。异胚轴的苦瓜亚科的胚胎仍处于鱼雷阶段，在种子萌发过程中或种子萌发后，根尖和茎尖分别由下胚轴顶端和两子叶之间形成。顶端生长太慢，不能形成营养枝，在单子叶植物中形成一个不发育的分生组织，称为槽分生组织b…。更多的植物直接在生殖枝顶端繁殖。凹槽分生组织被认为是与茎尖同源的，而不是新生的分生组织。增大的子叶是由位于子叶基部的基本分生组织的长时间活动产生的。基本分生组织的进化过程和潜在的机制仍有待于解决。但形态分析表明，其大的子叶与叶的发育方式有相似之处，两叶的生长主要是由于基部的分生细胞所致。它们的叶没有明显的板状分生组织，这是其他双子叶植物的典型特征。这可能是由于其子叶对板状分生组织的抑制比叶片更强烈，从而导致了异胚轴苦瓜亚科基本分生组织的形成。综上所述，单叶植株的进化可能是通过延缓胚胎发育，进而抑制营养枝生长而实现的。较少

Monophylly is exhibited in Monophyyllaea and in Streptocarpus (Gesneriaceae). Their plant body consists of a single large cotyledon. They never form stems or foliage leaves throughout their life history, and they produce inflorescences at the base of the cotyledon lamina. This research aims to clarify the evolution of the monophylly based on the molecular phylogenetic analysis and comparative morphogenesis. Research materials include not only anisocotylous Gesnerioideae but also isocotylous Cyrtandroideae. They were collected in Borneo, Malay Peninsula including Thai, Madagascar, South Africa, and Brazil on three botanical expeditions. The embryo of anisocotylous Gesnerioideae remains at the torpedo stage, and during or after seed germination the root apex and then shoot apex are formed from the hypocotyl tip and between the two cotyledons respectively. The shoot apex grows too slow to form the vegetative shoot, and in monophyllous plants a rudimentary meristem called groove meristem b … More ecomes directly the reproductive shoot apex. The groove meristem is considered to be homologous to the shoot apex, not a de novo meristem. The accrescent cotyledon is produced by the prolonged activity of the basal meristem located on the cotyledon base. The evolutionary course of the basal meristem and the underlying mechanism still remains to be solved. However, morphological analysis of caulescent species of Streptocarpus and Chirita shows that there is a similarity in the developmental mode between their large cotyledon and the foliage leaves ; the both leaves grow mainly due to the meristematic cells in the basal portion. Their foliage leaves do not have an apparent plate meristem typical of other dicotyledon-leaves. It seems likely that the suppression of the plate meristem occurred more strongly in their cotyledon than the foliage leaves, resulting in the establishment of the basal meristem in anisocotylous Gesnerioideae. In conclusion, one-leaf plants may have evolved through retardation of the embryogenesis and consequent suppression of the vegetative shoot growth. Less