PYI: Evolutionary History of Double Fertilization and the Endosperm

双受精和胚乳的进化史， 两个最重要的生殖特征， 将探讨显花植物的起源和成功。的 二次受精的发育命运 麻黄，一种不开花的种子植物，是麻黄科的基部成员。 现存的一个与非洲最接近的植物类群（买麻藤目） 植物，将进行研究。这项工作的最终目标是 确定麻黄第二次施肥产物 表现出类似胚乳的品质，这将支持一个新的 胚乳起源于开花前植物假说。 对这一假设的证据支持将从根本上改变 我们目前对进化历史和起源的概念 开花植物 第二组研究将检查非- 开花种子植物虽然超过百分之五十的 开花植物物种表现出某种类型的遗传 不相容机制，防止受精的 胚珠由花粉从密切相关的个人，证据 在不开花的种子植物中存在类似的不亲和系统， 是罕见的。使用道格拉斯冷杉的初步研究表明， 时间，记录的合子前对花粉质量的反应， 有花植物计划中的研究将审查竞争对手 花粉的混合遗传负荷的影响（以及雌性对 火炬松花粉的遗传组成 美国东南部的林业作物。

The evolutionary history of double fertilization and endosperm, two of the most important reproductive features associated with the origin and success of flowering plants will be examined. The developmental fate of the second fertilization in the genus Ephedra, a non-flowering seed plant and a basal member of the most closely related extant group of plants (Gnetales) to the angiosperms, will be studied. The ultimate goal of this work is to determine whether the second fertilization product in Ephedra exhibits endosperm-like qualities that would support a new hypothesis for a pre-flowering plant origin of endosperm. Evidential support for this hypothesis would fundamentally alter our current concepts of the evolutionary history and origins of flowering plants. A second set of studies will examine mate choice in non- flowering seed plants. Although more than fifty percent of flowering plant species exhibit some type of genetic incompatibility mechanism that prevents the fertilization of ovules by pollen from closely related individuals, evidence for similar incompatibility systems among non-flowering seed plants, is rare. Initial studies using Douglas fir have, for the first time, documented pre-zygotic response to pollen quality outside of flowering plants. Planned studies will examine the competitive effects of mixed genetic loads of pollen (and female response to the genetic constitution of pollen) in loblolly pine, a major forestry crop in the southeastern US.