Phylogenetic and Molecular Evolutionary Studies of Chloroplast DNA Variation in the Asteraceae

以往对菊科植物叶绿体DNA变异的研究在较高的分类水平上解决了许多系统问题。然而，主要的问题仍然存在于解决部落关系和单一的亚家族的乳酸菌。利用10种酶的比较限制性内切位点定位和两个基因（rpoC2和ndhF）的DNA测序，对菊科所有已知部落的代表物种的叶绿体DNA变异进行了扩展研究。这些新数据将与先前叶绿体DNA研究的数据相结合，以解决系统发育和分子进化问题。整合分子和形态数据将产生一个全面的系统发育和分类的菊科。精细限制位点和基因定位将使叶绿体基因组编码区和非编码区限制位点突变的系统发育效用的首次直接比较成为可能。同样，三个基因（rbcL, rpoC2, ndhF）的DNA序列的可用性将为被子植物系统发育研究中不同叶绿体基因的有用性提供急需的比较。限制性内切位点和序列数据的统计分析将用于检查叶绿体基因组序列进化的模式和速率。发现限制性内切位点突变位点的异质性，将为今后菊科和其他被子植物的分子系统研究提供有价值的信息。此外，对叶绿体基因组中具有不同功能和位置的三个叶绿体基因的编码序列和非编码序列内部和之间的核苷酸取代率和模式将获得新的见解。

Previous studies of chloroplast DNA variation in the Asteraceae have resolved many systematic issues at higher taxonomic levels. However, major problems persist in resolving tribal relationships and the monophyly of the subfamily Lactucoideae. An expanded examination of chloroplast DNA variation in the Asteraceae is proposed using comparative restriction site mapping of 10 enzymes and DNA sequencing of two genes (rpoC2 and ndhF) from representative species in all currently recognized tribes in the family. These new data will be combined with those from previous chloroplast DNA studies to address both phylogenetic and molecular evolutionary questions. Integration of molecular and morphological data will produce a comprehensive phylogeny and classification of the Asteraceae. Fine scale restriction site and gene mapping will enable the first direct comparisons of the phylogenetic utility of restriction site mutations in coding and noncoding regions of the chloroplast genome. Similarly, the availability of DNA sequences of three genes (rbcL, rpoC2, ndhF) will provide much needed comparisons of the usefulness of different chloroplast genes for phylogenetic studies in angiosperms. Statistical analyses of restriction site and sequence data will be used to examine the patterns and rates of sequence evolution in the chloroplast genome. Identification of heterogeneity in the location of restriction site mutations will provide valuable information for character analysis in future molecular systematic studies in the Asteraceae and other angiosperm families. Furthermore, new insights will be gained into the rates and patterns of nucleotide substitutions within and between coding and noncoding sequences from three chloroplast genes with different functions and locations in the chloroplast genome.