RUI: Pollen Developmental Evolution in the Basalmost Angiosperms - Nymphaeales and Amborella

近年来，人们对开花植物或被子植物的进化关系有了很大的了解，睡莲（Nymphaeales）和Amborella被确定为最早的分化谱系。睡莲分布在世界各地，包括两科八属，多年来一直引起植物学家的兴趣，部分原因是它们具有开花植物（双子叶和单子叶）两大类的特征。Amborella包括一个单一物种，是一种林下灌木，地理分布局限于新喀里多尼亚中部的山地热带雨林。对被子植物花粉发育的比较研究相对较少，但对了解关键性状的进化、进化关系或系统发育有重要贡献。然而，对睡莲和安波属植物的花粉研究相对较少。历史上，睡莲的花粉壁被报道为颗粒状，一种被认为是被子植物中原始的特征状态，而Amborella的花粉壁具有一种不寻常的结构，在其他现存的开花植物中似乎没有出现过。PI最近的一项研究表明，所有8属睡莲的成熟花粉都是小柱状的，这些花粉壁元件的发育模式和结构使它们表面上类似于颗粒。然而，这些成分的发育模式以及其他花粉性状在若虫科和安波科的发育模式尚不清楚。鉴于这两个原始类群在进化上的重要性，PI研究的总体重点是研究睡莲科和安柏科花粉的发育进化。该项目的主要目标是：(1)对两个关键的睡莲属（Cabomba和Nuphar）的花粉发育进行全面调查；(2)对其他属获得初步结果。拟议的研究将建立在PI实验室关于所有八个睡莲属的成熟花粉结构以及三个睡莲属（Cabomba， Nuphar和Euryale）的花粉发育的新数据的基础上。这项研究将结合使用显微技术，并将产生以前从未记录过的分辨率水平的数据。这些新数据将为在系统发育背景下研究花粉发育进化模式以及确定花粉发育特征与授粉生物学之间的功能相关性提供基础。

An understanding of the evolutionary relationships of flowering plants, or angiosperms, has been greatly improved in recent years, and water lilies (Nymphaeales) and Amborella have been identified as the earliest diverging lineages. Water lilies have a cosmopolitan distribution, comprise two families and eight genera, and have interested botanists for many years in part because they have characteristics of both major classes of flowering plants (dicots and monocots). Amborella includes a single species and is an understory shrub that is limited in geographic distribution to montane tropical rain forests in central New Caledonia. Comparative studies of pollen development in angiosperms are relatively rare, but make significant contributions to understanding the evolution of key characters, as well as evolutionary relationships, or phylogeny, when conducted. Relatively few pollen studies of water lilies and Amborella have been carried out, however. Historically, the pollen wall of water lilies has been reported as granular, a character state thought to be primitive among angiosperms, whereas that of Amborella has an unusual structure that does not appear to occur in other extant flowering plants. A recent study by the PI indicates that the mature pollen of all eight genera of water lilies is columellar, and that the developmental pattern and structure of these pollen wall elements makes them superficially resemble granules. The developmental pattern of these elements and that of other pollen characters in Nymphaeales and Amborella, however, are not well understood. Given the evolutionary importance of these two primitive groups, the overall focus of the PI's research is to study pollen developmental evolution in Nymphaeales and Amborella. The principal objectives of the proposed project are to (1) provide a comprehensive investigation of pollen development in two key water lily genera (Cabomba and Nuphar) and (2) obtain preliminary results on other genera. The proposed research will build on new data from the PI's laboratory about mature pollen structure in all eight water lily genera, as well as pollen development in three (Cabomba, Nuphar, and Euryale). The research will use combined microscopical techniques, and it will yield data at a level of resolution that has not been documented before. The new data will provide the foundation to examine the patterns of pollen developmental evolution within a phylogenetic context and determine functional correlations between pollen developmental characters and pollination biology.