Molecular Systematics of the Tribe Cichorieae (Asteraceae)

生菜族(菊科)是菊科向日葵大家族中一个重要的经济类群。以前的系统研究依赖于形态、细胞学和解剖学的传统特征，没有充分解决这一组的分类学和进化问题。康涅狄格大学的罗伯特·詹森博士和他的同事们将使用最近发展起来的分子方法来分析这些植物之间的系统发育关系。将在物种水平上分析核、核糖体和叶绿体DNA的变异，以评估主要分布在北美西部的16种银泡花(微丝海绵属)之间的进化关系。这项研究将包括确定该属几个物种的杂交和多倍体起源。这项研究的一个更广泛的重点是利用限制酶切点图谱和DNA测序分析生菜部落和推测相关的部落中70个属的叶绿体DNA变异。计算机辅助方法将被用来建立生菜部落的第一个系统发育树，这反过来将为对这个全球群体的历史生物地理做出预测性假设提供必要的框架。分子分析还将有助于解决菊苣亚科与向日葵家族其他16个部落的进化关系。该项目与P.I.及其同事之前对该家族的DNA分析相结合，还将生成有关开花植物家族中叶绿体DNA变异和进化的最大信息数据库。

The lettuce tribe (Cichorieae) is an economically important group within the large and biologically diverse sunflower family, Asteraceae. Previous systematic studies, relying on traditional characters of morphology, cytology, and anatomy, have not adequately resolved taxonomic and evolutionary problems in this group. Dr. Robert Jansen and his colleagues at the University of Connecticut will use recently developed molecular methods to analyze phylogenetic relationships among these plants. Variation in nuclear ribosomal and chloroplast DNA will be analyzed at the species level to assess evolutionary relationships among the 16 species of silver puffs (the genus Microseris) distributed primarily in western North America. This study will include the determination of hybrid and polyploid origins of several species in the genus. A broader focus of the study involves an analysis of chloroplast DNA variation in 70 genera in the lettuce tribe and putatively related tribes using restriction site mapping and DNA sequencing. Computer-assisted methods will be used to produce the first phylogenetic tree for the lettuce tribe, which in turn will provide the necessary framework for making predictive hypotheses about the historical biogeography of this worldwide group. The molecular analysis will also assist in resolving the evolutionary relationships of the Cichorieae to the other 16 tribes in the sunflower family. The project, combined with previous DNA analyses of this family by the P.I. and colleagues, will also generate the largest database of information concerning chloroplast DNA variation and evolution for any flowering plant family.