In the right place at the right time: Parnassia resolves the herkogamy dilemma by accurate repositioning of stamens and stigmas
In the right place at the right time: Parnassia resolves the herkogamy dilemma by accurate repositioning of stamens and stigmas
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在正确的时间、正确的地点：Parnassia 通过准确地重新定位雄蕊和柱头来解决雌雄同株的困境
DOI：
10.1093/aob/mct261
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发表时间：
2014-01-01
期刊：
影响因子：
4.2
通讯作者：
Huang, Shuang-Quan
中科院分区：
文献类型：
--
作者：
Armbruster, W. Scott;Corbet, Sarah A.;Huang, Shuang-Quan
在两性花中，花粉呈现和柱头可接受性的空间(雌雄)和时间(双性)分离被解释为减少雌雄功能之间的干扰。然而，空间分离导致了潜在的冲突：授粉精度降低，花粉可能被放置在传粉器上不同于柱头接触点的位置。为了更好地了解雌花如何解决这一冲突，对亚高山草本植物百合花进行了研究，其含蜜花表现出顺序的花药开裂(交错的花粉呈现)和雄蕊运动；通常每天一个新开裂的花药位于雌蕊群中央，而较老的雄蕊弯曲远离中心位置。开放的花被各种传粉者访问，其中大多数是苍蝇。结实率取决于传粉者(套袋花几乎不结实)和花粉限制(人工授粉比自由授粉增加结实率)。适应性精确度分析表明，雄蕊运动和花柱伸长(异花授粉)显著提高了授粉精确度。具体地说，开裂的花药和接受柱头相对于相反的性结构和传粉者位置在垂直和水平平面上定位准确。相反，花药和柱头之间的空间对应性在花药开裂前和雄蕊向外弯曲后以及柱头接受时期前后都显著降低。首次表明，在具有普遍授粉的花中，运动异花授粉和二倍体授粉相结合可以保持较高的授粉精度。交错的花粉和柱头呈现空间对应，既可以减少性别干扰，又可以提高授粉精度。
Spatial (herkogamy) and temporal (dichogamy) separation of pollen presentation and stigma receptivity have been interpreted as reducing interference between male and female functions in hermaphroditic flowers. However, spatial separation leads to a potential conflict: reduced pollination accuracy, where pollen may be placed in a location on the pollinator different from the point of stigma contact.To understand better how herkogamous flowers resolve this conflict, a study was made of a subalpine herb, Parnassia epunctulata, the nectariferous flowers of which exhibit sequential anther dehiscence (staggered pollen presentation) and stamen movements; usually one newly dehisced anther is positioned each day over the central gynoecium, while the older stamens bend away from the central position.The open flowers were visited by a variety of pollinators, most of which were flies. Seed set was pollinator-dependent (bagged flowers set almost no seeds) and pollen-limited (manual pollination increased seed set over open pollination). Analyses of adaptive accuracy showed that coordinated stamen movements and style elongation (movement herkogamy) dramatically increased pollination accuracy. Specifically, dehiscing anthers and receptive stigmas were positioned accurately in the vertical and horizontal planes in relation to the opposite sexual structure and pollinator position. By contrast, the spatial correspondence between anthers and stigma was dramatically lower before the anthers dehisced and after stamens bent outwards, as well as before and after the period of stigmatic receptivity.It is shown for the first time that a combination of movement herkogamy and dichogamy can maintain high pollination accuracy in flowers with generalized pollination. Staggered pollen and stigma presentation with spatial correspondence can both reduce sexual interference and improve pollination accuracy.