PYI: Evolutionary History of Double Fertilization and the Endosperm

双受精和胚乳的进化史，这两个与开花植物的起源和成功有关的最重要的生殖特征将被研究。麻黄属的第二次受精的发育命运将被研究，麻黄属是一种不开花的种子植物，也是现存的与被子植物关系最近的植物类群(Gnetales)的基本成员。这项工作的最终目标是确定麻黄中的第二受精产物是否表现出类似胚乳的品质，这将支持关于开花前植物胚乳起源的新假说。对这一假设的证据支持将从根本上改变我们目前对开花植物进化史和起源的概念。第二组研究将检验非开花种子植物的配偶选择。尽管超过50%的开花植物物种表现出某种类型的遗传不亲和机制，这种机制阻止了来自亲缘关系密切的个体的花粉受精，但没有开花的种子植物之间存在类似的不亲和系统的证据很少。利用道格拉斯冷杉进行的初步研究首次记录了开花植物以外的花粉质量对合子前的反应。计划中的研究将检验火炬松的混合遗传负荷(以及雌性对花粉遗传构成的反应)的竞争效应。火炬松是美国东南部的一种主要林业作物。

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.