DISSERTATION RESEARCH: The Effect of Mutation Rate on Mitochondrial Genome Evolution in the Angiosperm Genus Silene

分子进化领域的一个核心挑战是阐明在生命之树中存在的基因组组织、结构和功能方面产生巨大多样性的机制。该研究将通过比较线粒体突变率相差100倍以上的两种密切相关的开花植物（Silene latifolia和Silene noctiflora）的线粒体DNA序列、结构和功能，来研究突变率在不同基因组进化中的作用。对于每个物种，整个线粒体基因组将与叶绿体基因组的基因样本一起测序（物种之间的突变率没有任何差异），RNA编辑和内含子剪接的模式将通过cDNA测序来确定。鉴于开花植物的线粒体基因组与多细胞生物的核基因组之间的许多共性（如非编码DNA的增殖），本工作的意义将扩展到核基因组的进化和功能。阐明线粒体突变的动力学对于理解人类线粒体病理和植物细胞质雄性不育的机制基础具有潜在的重要意义，这一现象在农业系统中非常重要。带注释的线粒体基因组序列将在包括育种系统进化、超群体遗传学、细胞器传递、系统学和分子进化在内的各个研究领域对沉默研究界具有更广泛的价值。同时，该研究将为弗吉尼亚大学的本科生提供一个培训现代分子遗传学和生物信息学技术的宝贵机会。

A central challenge in the field of molecular evolution is to elucidate the mechanisms that have produced the enormous diversity in genome organization, structure and function that exists across the tree of life. The proposed research will examine the role of mutation rates in differentially shaping genome evolution by comparing the mitochondrial DNA sequence, structure and function for two closely related species of flowering plants (Silene latifolia and Silene noctiflora) that differ more than 100-fold in mitochondrial mutation rates. For each species, the entire mitochondrial genome will be sequenced along with a sample of genes from the chloroplast genome (which does not exhibit any differences in mutation rate between the species), and patterns of RNA editing and intron splicing will be identified by sequencing cDNA. Given the many commonalities between the mitochondrial genomes of flowering plants and the nuclear genomes of multicellular organisms (such as the proliferation of non-coding DNA), the implications of this work will extend to the evolution and function of the nuclear genome. Elucidating the dynamics of mitochondrial mutations is potentially important for understanding a wide variety of mitochondrial pathologies in humans and the mechanistic basis of cytoplasmic male sterility in plants, a phenomenon that is of great importance in agricultural systems. Annotated mitochondrial genome sequences will be of broader value to the Silene research community in diverse fields of study including breeding system evolution, metapopulation genetics, organelle transmission, systematics and molecular evolution. Also, the research will provide a valuable opportunity to train University of Virginia undergraduates in the modern techniques of molecular genetics and bioinformatics.