Hexose Transporter Genes and the Origin of Land Plants

陆生植物和动物一样，是通过形成胚胎开始生命的。陆地植物的胚胎，像许多但不是所有的动物胚胎一样，依附在母体上发育，并从母体获取食物，尤其是糖。与糖转运相关的遗传机制尚不清楚，特别是在形态简单的植物中，如苔藓植物（苔藓、苔类植物、角苔类植物），它们有胚胎，以及与苔藓密切相关但没有胚胎的藻类绿藻。在这项研究中，琳达·格雷厄姆和李·威尔科克斯将开始评估一组基因，即参与植物糖运输的己糖转运基因家族。他们将从藻类绿藻中获得己糖转运基因的分子序列信息。他们将利用这些序列构建系统发育树，并将这些树与其他来自不同基因序列的树进行比较，并从植物的形态和解剖特征中寻找更多的证据来支持藻类绿藻和苔藓植物密切相关的假设。他们将寻求对以下假设的支持：糖从亲本植物到胚胎的运输部分基于己糖转运基因产物（即蛋白质），这些基因来源于没有胚胎的植物（绿藻类），但在苔藓植物的亲本植物和发育中的胚胎之间的连接处特异性表达。这一结果将为陆地植物胚胎的起源、早期历史和发育提供重要的新信息，这是陆地植物生活史上最重要的事件之一。

9628869 GRAHAM Land plants, like animals, begin life by forming embryos. Land plant embryos, like many but not all animal embryos, develop while attached to a parent from which they obtain food, especially sugars. The genetic mechanisms associated with sugar transport are not well understood, especially in morphologically simple plants such as bryophytes (mosses, liverworts, hornworts), which have embryos, and charophycean green algae, which are closely related to mosses but do not have embryos. In this study, Linda Graham and Lee Wilcox will begin an evaluation of one set of genes, the hexose transporter gene family, that are involved in sugar transport in plants. They will obtain molecular sequence information from hexose transporter genes in charophycean green algae. They will use these sequences to construct phylogenetic trees, and compare these trees with others derived from sequences of different genes, and from the morphological and anatomical features of the plants, seeking additional support for the hypothesis that charophycean green algae and bryophytes are closely related. They will seek support for the hypothesis that sugar transport from parent plant to embryo is based in part upon hexose transporter gene products (i.e., proteins) that are derived from plants without embryos (charophycean green algae) but are specifically expressed at the junction between parent plant and developing embryo in bryophytes. The results should provide significant new information on the origin, early history, and development of the land plant embryo, one of the most fundamentally important events in the life history of land plants.