Key Message

PCD role in unisexual flowers.

Abstract

The developmental processes underlying the transition from hermaphroditism to unisexuality are key to understanding variation and evolution of floral structure and function. A detailed examination of the cytological and histological patterns involved in pollen and ovule development of staminate and pistillate flowers in the dioecious Opuntia robusta was undertaken, and the potential involvement of programmed cell death in the abortion of the sex whorls was explored. Flowers initiated development as hermaphrodites and became functionally unisexual by anthesis. Female individuals have pistillate flowers with a conspicuous stigma, functional ovary, collapsed stamens and no pollen grains. Male individuals have staminate flowers, with large yellow anthers, abundant pollen grains, underdeveloped stigma, style and an ovary that rarely produced ovules. In pistillate flowers, anther abortion resulted from the premature degradation of the tapetum by PCD, followed by irregular deposition of callose wall around the microsporocytes, and finally by microspore degradation. In staminate flowers, the stigma could support pollen germination; however, the ovaries were reduced, with evidence of placental arrest and ovule abortion through PCD, when ovules were present. We demonstrate that PCD is recruited in both pistillate and staminate flower development; however, it occurs at different times of floral development. This study contributes to the understanding of the nature of the O. robusta breeding system and identifies developmental landmarks that contribute to sexual determination in Cactaceae.

中文翻译：

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雌雄异株仙人掌仙人掌花的雄蕊和雌蕊花的比较发育。

关键信息

PCD在单性花中的作用。

抽象

从雌雄同体向单性转变的发展过程是理解花卉结构和功能变异和进化的关键。对雌雄异体仙人掌花的雄蕊和雌蕊花的花粉和胚珠发育所涉及的细胞学和组织学模式的详细检查进行了研究，并探讨了程序性细胞死亡在性涡旋流产中的潜在参与。花由雌雄同体开始发育，并由于花药而在功能上变得单性。女性个体的雌蕊花具明显的柱头，有功能的子房，雄蕊塌陷，没有花粉粒。雄性花具花基，具大的黄色花药，花粉粒丰富，柱头不发达，花柱和子房很少产生胚珠。在雌蕊花中，花药流产是由于PCD引起绒毡层过早降解，随后是ose壁在微孢子细胞周围的不规则沉积，最后是小孢子降解。在发芽的花朵中，柱头可以支撑花粉的萌发。但是卵巢减少了 当存在胚珠时，有通过PCD引起胎盘停滞和胚珠流产的证据。我们证明PCD是在雌蕊和稳定花发育中募集的；然而，它发生在花发育的不同时间。这项研究有助于了解自然界的本质。O.robusta育种系统，识别有助于仙人掌科中性决定的发育标志。