Style head in Apocynaceae: a very complex secretory activity performed by one tissue
Style head in Apocynaceae: a very complex secretory activity performed by one tissue
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夹竹桃科的花柱头：由一个组织执行的非常复杂的分泌活动
DOI：
10.4081/ejh.2024.4027
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发表时间：
2024
影响因子：
2
通讯作者：
Diego Demarco
中科院分区：
文献类型：
--
作者：
Danielle Maximo;Diego Demarco
婚腺体种类繁多，与不同的授粉机制有关。花药到柱头的花粉传递机制的专一性越强，花的形态精细程度越高，腺体的功能越复杂。在夹竹桃科中，授粉机制达到了极端的专一性，这一事实只有在极端的形态合并体和丰富的花腺的作用下才有可能。虽然这些腺体的类型不同，但绝大多数腺体只在表皮中有分泌细胞。一般来说，这些表皮细胞同时产生许多不同的化合物，此前的研究表明，在花柱头中，表皮的功能复杂性变得更大。花柱头状花序有四种类型，它们在分泌和散粉机制方面具有不同程度的功能复杂性。其分泌物为I、II和III型液体，花粉通过花柱头分泌的分泌物散布并附着在传粉器上。在类型I和V中，分泌物变硬并获得特定的形状，由相邻花器官的空间约束塑造。这种进化变化伴随着分泌细胞结构和排列的变化，以及花粉聚集和柱头位置的变化。组织化学分析表明，分泌物是混合的和高度复杂的，特别是在花柱头型IV型中，分泌物被称为翻译，由附着在传粉器上的坚硬的中央部分和附着在两个授粉细胞上的两个尾部组成。译者在不同的部分有不同的构成。需要进一步的研究来回答由于发现这种高度功能复杂的分泌组织而产生的新问题。
Nuptial glands are very diverse and associated with different pollination mechanisms. The greater the specificity in the pollen transfer mechanism from anther to stigma, the greater the morphological elaboration of flowers and functional complexity of the nuptial glands. In Apocynaceae, pollination mechanisms reached an extreme specificity, a fact that was only possible due to an extreme morphological synorganization and a profusion of floral glands. Although these glands are of different types, the vast majority have secretory cells only in the epidermis. In general, these epidermal cells produce many different compounds at the same time, and previous studies have demonstrated that in the style head, the functional complexity of epidermis has become even greater. Four types of style head are found in the family, which have different degrees of functional complexity in relation to the secretion produced and pollen dispersal mechanism. The secretion is fluid in types I, II and III, and the pollen is dispersed and adhered to the pollinator by the secretion produced by the style head. In type I V, the secretion hardens and acquires a specific shape, moulded by the spatial constraints of the adjacent floral organs. This evolutionary alteration is accompanied by changes in the structure and arrangement of the secretory cells, as well as in pollen aggregation and position of stigma. Histochemical analysis has shown that the secretion is mixed and highly complex, especially in the style head type IV, where the secretion, called translator, is formed by a rigid central portion, which adheres to the pollinator, and two caudicles that attach to two pollinia. The translator has a distinct composition in its different parts. Further studies are needed to answer the new questions that have arisen from the discovery of this highly functional complexity of the secretory tissue.