DISSERTATION RESEARCH: Phylogenetically-Based Analysis of Plastid Genome Evolution in the Photosynthetically Variable Parasitic Flowering Plant Genus, Cuscuta

宾夕法尼亚州立大学的Claude dePamaret博士和Joel McNeal先生获得了一笔赠款，用于研究一组被称为菟丝子的寄生植物的不同物种之间的关系，以及产生光合作用所需蛋白质的基因在谱系中的物种之间的差异。菟丝子，这是藤蔓，只有微小的，无用的叶子，没有任何根，附着在其他植物的茎上，并依赖于这些宿主的所有水分，无机营养素，以及大多数，如果不是全部的话，碳水化合物的需求。 由于这种习惯，寄生虫减少了为自己进行光合作用的需要。 位于叶绿体（植物细胞的光合区室）内的基因在开花植物中高度保守，因为这些基因中的大多数是从阳光和大气二氧化碳中产生碳水化合物所必需的。 然而，这些基因在不同的菟丝子之间存在很大程度的变异，表明不同的物种可能表现出不同的光合能力。 通过研究哪些基因在不同的菟丝子物种和相关的非寄生植物的叶绿体中是很保守的，了解哪些基因对光合作用是最重要的，哪些基因是更消耗将获得。 这些数据将通过与其他寄生植物谱系的比较进一步验证。 此外，菟丝子物种之间的关系的知识可能最终被证明是有价值的控制这些寄生杂草，其中许多严重的农业损害和联邦指定的有毒杂草。 从营养独立到寄生的转变在植物和许多其他生命谱系中发生过无数次。 这种寄生植物群将作为一个很好的模型来研究伴随这种转变的遗传变化。

A grant has been awarded to Dr. Claude dePamphilis and Mr. Joel McNeal at Pennsylvania State University to study how different species of a group of parasitic plants known as dodders are related to each other and how genes that produce proteins necessary for photosynthesis differ between species in the lineage. Dodders, which are vines that possess only tiny, useless leaves and no roots whatsoever, attach to the stems of other plants and are dependent on these hosts for all of their water, inorganic nutrients, and most, if not all, of their carbohydrate needs. Because of this habit, the parasites have a reduced need to photosynthesize for themselves. Genes located within chloroplasts, the photosynthetic compartments of plant cells, are highly conserved across flowering plants because most of these genes are necessary for carbohydrate production from sunlight and atmospheric carbon dioxide. However, a large degree of variation exists in these genes between different dodders, indicating that different species may demonstrate differing abilities to photosynthesize. By examining which genes are well conserved within chloroplasts of different dodder species and related non-parasitic plants, an understanding of which genes are most important for photosynthesis and which genes are more expendable will be gained. These data will be verified further by comparison with other parasitic plant lineages. Furthermore, knowledge of the relationships between dodder species may eventually prove to be valuable to the control of these parasitic weeds, many of which do serious agricultural damage and are federally designated noxious weeds. The transition from being nutritionally independent to being parasitic has occurred numerous times within plants and also within many other lineages of life. This parasitic plant group will serve as an excellent model to study the genetic changes that accompany this transition.