Molecular Systematics and Chloroplast DNA Variation in Parasitic Scrophulariaceae/Orobanchaceae

对叶绿体DNA(CpDNA)变异的研究有助于阐明许多植物群的系统发育关系。然而，最常见类型的cpDNA数据不能应用于完全非光合作用的寄生植物谱系。我建议使用一种新的数据来源，非光合作用叶绿体基因序列，来研究一个包含光合作用和非光合作用形式的家族的系统发育关系。玄参科和防己科是这些研究的理想植物，因为它们含有具有广泛寄生行为的植物，包括一些对重要作物植物具有高度破坏性的植物。此外，这类植物的cpDNA结构和基因含量与光合作用的丧失有关，表现出显著的变异。包括基因测序和cpDNA作图在内的多重方法将研究这一群体的分子系统发育，并全面描述其cpDNA结构和基因含量的变异。这项研究将集中在将玄参科和(非光合作用的)萝卜科统一起来的关键的“过渡”属，但将包括这两个组中的物种和外群分类群。这项研究应该取得的重大进展包括：(1)可以在植物家族中使用的高效分子系统方法，甚至包括非光合作用植物在内的“麻烦”方法。(2)了解最重要的寄生植物类群的系统发育关系和性状进化的机会。(3)对cpDNA分子变异的动力学和机制有了更深入的了解。

Studies of chloroplast DNA (cpDNA) variation have helped to clarify phylogenetic relationships in many plant groups. However, the most common types of cpDNA data cannot be applied to parasitic plant lineages that are completely non-photosynthetic. I propose to use a new source of data, sequences of nonphotosynthetic chloroplast genes, to investigate phylogenetic relationships in a family containing photosynthetic and nonphotosynthetic forms. Scrophulariaceae and Orobanchaceae are ideal for these studies because they contain plants with a wide range of parasitic behaviors, including some that are highly destructive to important crop plants. Additionally, plants in this group display remarkable variation in cpDNA structure and gene content associated with the loss of photosynthesis. A multiple approach involving gene sequencing and cpDNA mapping will examine the molecular phylogeny of this group and fully describe its variation in cpDNA structure and gene content. The study will focus on critical "transition" genera that unify the Scrophulariaceae with the (nonphotosynthetic) Orobanchaceae, but will include species in both groups plus outgroup taxa. Significant developments that should derive from this research include: (1) Efficient molecular systematic approaches that can be used within plant families, even "troublesome" ones that include nonphotosynthetic plants. (2) Opportunities to learn much about the phylogenetic relationships and character evolution within the most economically important group of parasitic plants. (3) A much deeper understanding of the dynamics and mechanisms of cpDNA molecular variation.