Molecular Systematics and Chloroplast DNA Variation in Parasitic Scrophulariaceae/Orobanchaceae

叶绿体DNA （cpDNA）变异的研究有助于阐明许多植物类群的系统发育关系。然而，最常见的cpDNA数据类型不能应用于完全不进行光合作用的寄生植物谱系。我建议使用一个新的数据来源，非光合叶绿体基因序列，来研究一个包含光合和非光合形式的家族的系统发育关系。玄参科和圆蕨科是这些研究的理想对象，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具有高度破坏性的植物。此外，这组植物在cpDNA结构和与光合作用丧失相关的基因含量方面表现出显著的差异。包括基因测序和cpDNA定位在内的多种方法将检查这一群体的分子系统发育，并充分描述其在cpDNA结构和基因含量方面的变化。这项研究将集中在关键的“过渡”属上，这些属将玄参科与（非光合作用的）Orobanchaceae统一起来，但将包括两组中的物种以及群外分类群。从这项研究中应该得到的重大进展包括：(1)有效的分子系统方法可用于植物科，甚至包括非光合植物在内的“麻烦”植物。(2)有机会了解寄生植物中最重要的经济类群的系统发育关系和特征进化。(3)对cpDNA分子变异的动力学和机制有了更深入的认识。

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.