Silene latifolia and Microbotryum violaceum : Molecular, cellular and Morphological studies on plant sexuality and parasitic fungus operating it.

Silene latifolia 和 Microbotryum violaceum ：植物性行为及其寄生真菌的分子、细胞和形态学研究。

基本信息

批准号：
17370022
负责人：
KAWANO Shigeyuki
金额：
$ 9.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

The development of male organs is induced in female flowers of the dioecious plant Silene latifolia by infection with the smut fungus Microbotryum violaceum. Stamens in a healthy female flower grow only to stage 6, whereas those in an infected female flower develop to the mature stage (stage 12), at which the stamens are filled with fungal teliospores instead of pollen grains.Using natural scanning electron microscopy, Nomarski interference microscopy, and fluorescence microscopy, we investigated the morphological modifications of the host plant resulting from this parasitism and the localization of smut hyphae in the flower bud. Flowers of infected plants lasted significantly longer than those of healthy plants, probably because the infection strengthened floral organs, such as the flower base and the anther filaments. Smut hyphae were observed throughout all organs of the young flower buds of infected plants, including sepals, petals, stamens, and pistil primordia. In healthy female … More flowers, anthers initiated sporogenous cell formation, but lacked parietal cell layers. By contrast, the parietal cell layers of infected female flowers differentiated into tapetal tissue, middle cell layers, and endothecial layers, as in the anthers of healthy male flowers. Smut spore formation in the infected anther was initiated in intercellular regions between the sporogenous cells, resulting in degeneration of premature sporogenous cells, tapetal tissue, and middle cell layers. The development of the endothecial layers and epidermis in the infected anther were morphologically normal.To investigate these host-parasite interactions, young floral buds and fungus-induced anthers of infected female flowers were examined by electron microscopy following fixation by a high-pressure freezing method. Using this approach, we found that parasitic hyphae of this fungus contain several extracellular vesicles and have a consistent appearance up to stage 8. At that stage, parasitic hyphae are observed adjacent to dying sporogenous cells in the infected female anther. At stage 9, an increased number of dead and dying sporogenous cells is observed, among which the sporogenous hyphae of the fungus develop and form initial teliospores. Several types of electron-dense material are present in proximity to some fungi at this stage. The initial teliospores contain two types of vacuoles, and the fungus cell wall contains abundant carbohydrate, as revealed by silver protein staining. The sporogenous cell is probably sensitive to infection by the fungus, resulting in disruption. In addition, the fungus accelerates cell death in the anther and utilizes constituents of the dead host cell to form the mature teliospore.Silene latifolia is a dioecious plant in which sex is determined by X and Y chromosomes. Expression of the B-function gene SLM2, an ortholog of PISTILLATA (P1) in Arabidopsis, was examined by in situ hybridization. SLM2 was not expressed in suppressed stamens of female flowers, but was expressed in developing stamens of smut-infected female flowers. These results indicate that the control of SLM2 is independent of the presence of the Y chromosome. Smut-infected females provide a useful system for clarifying the relationship between the B-function gene and the sex determination factor. Less

雌雄异株植物 Silene latifolia 的雌花中，通过黑粉菌 Microbotryum violaceum 的感染，诱导雄性器官的发育。健康雌花中的雄蕊仅生长到第 6 阶段，而受感染雌花中的雄蕊则发育到成熟阶段。阶段12），此时雄蕊充满真菌冬孢子而不是花粉粒。使用自然扫描电子显微镜，Nomarski干扰通过显微镜和荧光显微镜，我们研究了这种寄生引起的寄主植物的形态变化以及黑穗病菌丝在花芽中的定位，受感染植物的花比健康植物的花持续时间明显更长，这可能是因为感染增强了花器官。，如花基部和花药丝，在受感染植物的幼花蕾的所有器官中都观察到，包括萼片、花瓣、在健康的雌花中，花药启动产孢细胞形成，但缺乏壁细胞层。相比之下，受感染的雌花的壁细胞层分化为绒毡层组织、中间细胞层和内壁细胞层。与健康雄花的花药中一样，受感染的花药中黑穗病孢子的形成是在产孢细胞之间的细胞间区域开始的，导致过早产孢的退化。受感染花药中的细胞、绒毡层组织和中细胞层的发育形态正常。为了研究这些宿主与寄生虫的相互作用，对受感染雌花的幼花芽和真菌诱导的花药进行了电子检查。通过高压冷冻方法固定后的显微镜检查，我们发现这种真菌的寄生菌丝含有多个细胞外囊泡，并且在阶段之前具有一致的外观。 8.在该阶段，在受感染的雌性花药中，在死亡的产孢细胞附近观察到寄生菌丝。在第9阶段，观察到死亡和垂死的产孢细胞数量增加，其中真菌的产孢菌丝发育并形成初始冬孢子。在此阶段，一些真菌附近存在几种类型的电子致密材料。最初的冬孢子包含两种类型的液泡。银蛋白染色显示，真菌细胞壁含有丰富的碳水化合物，产孢细胞可能对真菌的感染敏感，从而导致破坏。此外，真菌加速花药中的细胞死亡，并利用死亡宿主细胞的成分。形成成熟的冬孢子。大叶硅烯是一种雌雄异株植物，其性别由 X 和 Y 染色体的 B 功能基因 SLM2（PISTILLATA 的直系同源物）的表达决定。 (P1)在拟南芥中，通过原位杂交检测SLM2在受抑制的雌花雄蕊中不表达，但在黑穗病感染的雌花的发育雄蕊中表达。这些结果表明SLM2的控制与存在无关。黑穗病感染的女性提供了一个有用的系统来阐明 B 功能基因和性别决定因素之间的关系。