Seeking the Phylogenetic Root of the Monocots: A Study of Paleoherb Genomes

[873724]杜瓦尔单子叶植物构成了一个由5万种植物组成的定义明确的群体，它们无疑是从同一个祖先进化而来的。然而，植物学家仍在寻找与单子科植物关系最密切的双子科植物，即所谓的单子科植物姐妹群。虽然单子叶的基础群现在已知是Acoranan谱系，但关于该群体祖先特征的细节仍然不确定。单子叶植物被认为是古草本植物进化辐射的一部分。利用叶绿体、细胞核和线粒体这三个植物基因组的关键花性状和基因，探索50多种古草本植物之间的关系。每个物种将确定大约6000个碱基对的核苷酸序列。这些数据将用于研究古草本植物的系统发育模式，并确定单子科植物的双子科姐妹群。单子科植物双科姐妹群的系统发育假说得到了强有力的支持，这将对我们理解古草本植物的分子进化和系统分类学有重要的贡献，并为系统学家进一步的进化研究提供一个合适的参考群体。一旦系统发育问题得到解答，就可以确定相关姐妹类群分类单元的有机体特征，以确定哪些特征对这个大群体的适应性辐射至关重要。对这些性状的分子研究可以确定对单株基本形态有重要影响的关键基因。最后，对单子叶植物的起源和辐射提出新的、更有支持的假设。

9873724 Duvall The monocots constitute a well-defined group of 50,000 plant species that have undoubtedly evolved from a single ancestor. However, botanists are stillunsure of the most closely related dicot, the so-called sister group of the monocots. Although the basal group of monocots is now known to be the Acoranan lineage, details regarding ancestral characters of the group are still uncertain.The monocots are known to be part of a greater evolutionary radiation of ancient herbaceous species, the paleoherbs. Relationships within over fifty species of paleoherbs will be explored using key floral characters and genes from the three plant genomes, the chloroplast, the nucleus, and the mitochondrion. Approximately 6000 base pairs of nucleotide sequence will be determined for each species. These data will be used to study phylogenetic patterns within paleoherbs and to identify the dicot sister group to themonocots.A strongly supported phylogenetic hypothesis for the dicot sister group to the monocots will be a significant contribution to our understanding of the molecular evolution and systematics of the paleoherbs and provide systematists with an appropriate reference group for further evolutionary studies. Once the phylogenetic questions have been answered, organismal characteristics in the relevant sister group taxon can be identified to determine which characters were critical to the adaptive radiation of this large group. Molecular investigation of these characters may identify key genes important to the fundamental monocot morphology. Finally, new and better supported hypotheses for the origin and radiation of monocots will be formulated.