Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
Plant J. 2013 May;74(4):615-25. doi: 10.1111/tpj.12150. Epub 2013 Mar 13.
The structural homology of the daffodil corona has remained a source of debate throughout the history of botany. Over the years it has been separately referred to as a modified petal stipule, stamen and tepal. Here we provide insights from anatomy and molecular studies to clarify the early developmental stages and position of corona initiation in Narcissus bulbocodium. We demonstrate that the corona initiates as six separate anlagen from hypanthial tissue between the stamens and perianth. Scanning electron microscope images and serial sections demonstrate that corona initiation occurs late in development, after the other floral whorls are fully developed. To define more precisely the identity of the floral structures, daffodil orthologues of the ABC floral organ identity genes were isolated and expression patterns were examined in perianth, stamens, carpel, hypanthial tube and corona tissue. Coupled with in situ hybridisation experiments, these analyses showed that the expression pattern of the C-class gene NbAGAMOUS in the corona is more similar to that of the stamens than that of the tepals. In combination, our results demonstrate that the corona of the daffodil N. bulbocodium exhibits stamen-like identity, develops independently from the orthodox floral whorls and is best interpreted as a late elaboration of the region between the petals and stamens associated with epigyny and the hypanthium.
在植物学的历史中，黄水仙的副花冠的结构同源性一直是一个争论的来源。多年来，它分别被称为修饰的花瓣托叶、雄蕊和花被片。在这里，我们从解剖学和分子研究中提供了见解，以阐明 Narcissus bulbocodium 中副花冠的早期发育阶段和起始位置。我们证明，副花冠从雄蕊和花被片之间的花托组织中单独的六个原基开始形成。扫描电子显微镜图像和连续切片显示，副花冠的起始发生在其他花轮完全发育之后的发育后期。为了更精确地定义花结构的身份，我们分离了黄水仙 ABC 花器官身份基因的直系同源物，并检查了花被片、雄蕊、心皮、花托管和副花冠组织中的表达模式。这些分析与原位杂交实验相结合，表明 C 类基因 NbAGAMOUS 在副花冠中的表达模式与雄蕊的表达模式更相似，而不是与花被片的表达模式相似。综合来看，我们的结果表明，黄水仙 N. bulbocodium 的副花冠表现出类似雄蕊的特征，独立于正统的花轮发育，最好解释为与上位花和花托相关的花瓣和雄蕊之间区域的后期发育。
