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

小行星9811362 要求支持研究的历史组I内含子发现在一个相同的位置在线粒体基因细胞色素氧化酶I（coxI）的不同开花植物。 该内含子与真菌中已被充分研究的感染性内含子同源，并具有其关键结构元件。 内含子存在于许多不相关的有花植物谱系中，而在绝大多数被检测的有花植物中不存在。 令人惊讶的是，内含子特别集中在寄生植物中，这些植物与其他植物和真菌有密切的共生关系。 这种模式和寄生植物的生物学特征表明，一些寄生植物能够掺入外源DNA序列和/或可能在向宿主谱系的遗传转移中发挥内含子来源的作用。 这项拟议的研究将测试基于生物学的假设，这些假设可能解释植物谱系中coxI内含子的存在和运动。 收集的数据将定义的精确分布的内含子在寄生和非寄生植物群，基因和细胞的位置的序列，和系统发育比较coxI内含子和外显子序列。 还将检查第二个线粒体基因atpA，以提高coxI外显子的系统发育分辨率和可靠性（即，植物线粒体）的历史。 这项研究将代表植物线粒体基因及其内含子的第一个全面的分析，其结果将有重要的意义，为我们了解细胞器遗传学，移动的遗传元件，分子进化和系统学的基本问题。 此外，该项目对社会的更广泛意义包括：1）培养本科生、研究生和博士后科学家; 2）鉴定植物细胞器序列中的入侵遗传因子的潜力; 3）发展系统发育方法来研究内含子，这可能对理解生物学、农业和医学中的其他入侵因子有更广泛的应用; 4）有助于了解寄生植物，这可能有助于控制农业中的有害寄生杂草。

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.