Gotelli M M, Lattar E C, Zini L M, Galati B G
Cátedra de Botánica General, Depto. de Recursos Naturales y Ambiente, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
CONICET, Buenos Aires, Argentina.
Plant Reprod. 2017 Dec;30(4):155-170. doi: 10.1007/s00497-017-0312-3. Epub 2017 Nov 7.
The style morphology and anatomy vary among different species. Three basic types are: open, closed, and semi-closed. Cells involved in the pollen tube pathway in the different types of styles present abundant endoplasmic reticulum, dictyosomes, mitochondria, and ribosomes. These secretory characteristics are related to the secretion where pollen tube grows. This secretion can be represented by the substances either in the canal or in the intercellular matrix or in the cell wall. Most studies suggest that pollen tubes only grow through the secretion of the canal in open styles. However, some species present pollen tubes that penetrate the epithelial cells of the canal, or grow through the middle lamella between these cells and subepithelial cells. In species with a closed style, a pathway is provided by the presence of an extracellular matrix, or by the thickened cell walls of the stylar transmitting tissue. There are reports in some species where pollen tubes can also penetrate the transmitting tissue cells and continue their growth through the cell lumen. In this review, we define subtypes of styles according to the path of the pollen tube. Style types were mapped on an angiosperm phylogenetic tree following the maximum parsimony principle. In line with this, it could be hypothesized that: the open style appeared in the early divergent angiosperms; the closed type of style originated in Asparagales, Poales, and Eudicots; and the semi-closed style appeared in Rosids, Ericales, and Gentianales. The open style seems to have been lost in core Eudicots, with reversions in some Rosids and Asterids.
花柱的形态和解剖结构在不同物种间存在差异。基本类型有三种：开放型、闭合型和半闭合型。在不同类型花柱中参与花粉管生长途径的细胞含有丰富的内质网、高尔基体、线粒体和核糖体。这些分泌特征与花粉管生长部位的分泌作用有关。这种分泌作用可由花柱道、细胞间基质或细胞壁中的物质体现。大多数研究表明，在开放型花柱中花粉管仅通过花柱道的分泌物生长。然而，一些物种的花粉管会穿透花柱道的上皮细胞，或通过这些细胞与上皮下细胞之间的中层片层生长。在闭合型花柱的物种中，细胞外基质的存在或花柱传递组织增厚的细胞壁提供了一条途径。有报道称，在一些物种中花粉管也能穿透传递组织细胞并通过细胞腔继续生长。在本综述中，我们根据花粉管的路径定义花柱的亚型。按照最大简约原则，将花柱类型映射到被子植物系统发育树上。据此可以推测：开放型花柱出现在早期分化的被子植物中；闭合型花柱起源于天门冬目、禾本目和真双子叶植物；半闭合型花柱出现在蔷薇类植物、杜鹃花目和龙胆目植物中。开放型花柱似乎在核心真双子叶植物中消失了，但在一些蔷薇类植物和菊类植物中有回复现象。
