Evolution of a Mitochondrial Gene and its Intron in Parasitic and Nonparasitic Plants

9811362为了研究在不同开花植物的线粒体基因细胞色素氧化酶I(Coxi)中同一位置发现的I组内含子的历史，需要dePamPhilis的支持。该内含子与真菌中一个已被充分研究的感染性内含子同源，并具有关键的结构元件。内含子存在于许多无关的开花植物谱系中，而在所研究的绝大多数开花植物中都不存在。令人惊讶的是，内含子尤其集中在寄生植物中，这些寄生植物与其他植物和真菌有着密切的共生关系。这种模式和寄生植物生物学的特征表明，一些寄生植物能够整合外来DNA序列和/或可能在向宿主谱系的遗传转移中发挥了内含子来源的作用。这项拟议的研究将检验基于生物学的假说，这些假说可能解释Coxi内含子在植物谱系中的存在和移动。收集的数据将确定内含子在寄生和非寄生植物群中的准确分布，序列的基因和细胞定位，以及Coxi内含子和外显子序列的系统发育比较。第二个线粒体基因ATPA也将被检测，以提高Coxi外显子(即植物线粒体)历史的系统发育分辨率和可靠性。这项研究将是对植物线粒体基因及其内含子的首次全面分析，其结果将对我们理解细胞器遗传学、可移动遗传元件以及分子进化和系统学的基本问题具有重要意义。此外，该项目对社会的更广泛意义包括：1)培训本科生、研究生和博士后科学家；2)鉴定植物细胞器序列中入侵的遗传元素的潜力；3)开发研究内部入侵的系统发育方法，这些方法可能会在理解生物学、农业和医学中的其他入侵因素方面具有更广泛的应用；4)有助于了解寄生植物，这可能有助于努力控制农业中有害的寄生杂草。

9811362 dePamphilis Support is requested to study the history of a Group I intron found at an identical location in the mitochondrial gene cytochrome oxidase I (coxI) of diverse flowering plants. The intron is homologous with and has key structural elements of a well-studied infectious intron in fungi. The intron occurs in numerous unrelated lineages of flowering plants, while being absent from the vast majority of flowering plants examined. Surprisingly, the intron is particularly concentrated in parasitic plants, which have intimate symbiotic associations with other plants and fungi. This pattern, and features of the biology of parasitic plants, suggests the possibility that some parasitic plants are capable of incorporation of foreign DNA sequences and/or may have played a role as an intron source in genetic transfers to host lineages. The proposed research will test biologically-based hypotheses that may explain the presence and movement of the coxI intron among plant lineages. The data collected will define the precise distribution of the intron across parasitic and nonparasitic plant groups, the genic and cellular location of the sequences, and phylogenetic comparisons of coxI intron and exon sequences. A second mitochondrial gene, atpA, will also be examined, to improve the phylogenetic resolution and reliability of the coxI exon (ie., plant mitochondrial) history. This research will represent the first comprehensive analysis of a plant mitochondrial gene and its intron; the results will have important implications for our understanding of organelle genetics, mobile genetic elements, and fundamental problems of molecular evolution and systematics. In addition, the broader significance of this project to society includes: 1) Training of undergraduate, graduate, and postdoctoral scientists; 2) Potential for the identification of invasive genetic elements in plant organelle sequences, 3) Development of phylogenetic approaches to the study of intr ons that may have broader application to understanding other invasive elements in biology, agriculature, and medicine; 4) Contributing to an understanding of parasitic plants, which could aid efforts to control harmful parasitic weeds in agriculture.