Molecular Systematics of the Tribe Cichorieae (Asteraceae)

莴苣族（苣科）是向日葵科中一个经济上重要的群体，具有丰富的生物多样性。以往的系统研究，依赖于形态学、细胞学和解剖学的传统特征，并没有充分解决这个群体的分类和进化问题。康涅狄格大学的Robert Jansen博士和他的同事将使用最近开发的分子方法来分析这些植物之间的系统发育关系。核糖体和叶绿体DNA的变异将在物种水平上进行分析，以评估主要分布在北美西部的16种银泡虫（Microseris属）之间的进化关系。本研究将包括确定该属几个物种的杂交和多倍体起源。该研究的一个更广泛的重点涉及使用限制性位点定位和DNA测序分析生菜部落和推定相关部落的70个属的叶绿体DNA变异。计算机辅助方法将用于生成莴苣部落的第一个系统发育树，这反过来将为对这一世界性群体的历史生物地理学做出预测性假设提供必要的框架。分子分析也将有助于解决知音科与向日葵家族中其他16个部落的进化关系。该项目与P.I.及其同事先前对该家族的DNA分析相结合，也将产生有关任何开花植物家族叶绿体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.