Phylogenetics of Diploid and Allopolyploid Hibiscus Sect. Furcaria (Malvaceae)

[10823]小型植物系统学领域的主要焦点之一是了解现存物种之间的系谱关系，并了解这些物种产生的过程。本项目研究的是锦葵科木槿属的一组植物。这一组木槿，分类归类为木槿节Furcaria，包括超过100种分布在世界各地。已知这些物种中有十个是二倍体（有“正常”的两组染色体），而其余的是多倍体，有四组、六组、八组或十组染色体。据推测，这些多倍体起源于两个不同物种之间的杂交，随后后代的染色体加倍。在这个群体中，多倍体物种比二倍体物种数量更多，可能是由于额外的染色体组提供了遗传多样性。本项目的目的是首先阐明该群体中二倍体物种之间的关系。随后选择的多倍体物种也将被分析——每个多倍体将包含来自其每个亲本的基因，其中一些可能是诊断性的，这将允许识别每个多倍体物种的杂交亲本。最终，这些数据将用于解决物种分类群的分类问题，研究这些关系中固有的地理模式，以及形态特征的演变。这些分析中使用的数据包括核糖体基因和叶绿体基因标记，以及酒精脱氢酶基因家族核编码基因的DNA序列。分子生物学为研究人员提供了丰富的遗传数据，特别是DNA序列，用于分析物种之间的关系。植物系统学家主要依靠两种来源的序列：叶绿体DNA和核糖体DNA，这两种DNA在遗传上都是易于分离的。然而，在植物核基因组的其余部分，仍有大量的DNA序列资源尚未得到相对的开发。这些类型的序列在很大程度上被系统学家所忽视，主要是因为它们在遗传上更复杂，因此更难分离和表征。然而，从这些序列中获得的数据的数量和质量可以抵消这些额外的实验努力。Randall Small博士先前对棉花及其相关物种（棉属，也属于锦葵科）的研究表明，这些类型的序列可以可靠地分离出来，并且对系统研究非常有用。由于棉花作为一种作物的重要性，丰富的棉花遗传学知识加速了这些研究。为了方便将这些知识从像棉花这样的知名群体转移到不太有特征的野生物种群体（如芙蓉节Furcaria），目前的项目将利用对在棉花中开发的酒精脱氢酶基因家族的理解来解决物种关系。因此，这个项目提供了一个直接的测试，从一个遗传特征良好的群体（棉花）收集到一个不太了解的群体（芙蓉部分Furcaria）的信息可转移性。

0108231Small One of the primary foci of the field of plant systematics is to understand the genealogical relationships among present day species, and to understand the processes that gave rise to those species. This project is focused on a group of species in the genus Hibiscus in the plant family Malvaceae (the Mallow family). This group of Hibiscus, taxonomically classified as Hibiscus section Furcaria, includes over 100 species that are distributed worldwide. Ten of these species are known to be diploid (having the "normal" two sets of chromosomes), while the remainder are polyploid having four, six, eight or ten sets of chromosomes. These polyploids are hypothesized to have originated through hybridization between two different species followed by chromosome doubling in the offspring. In this group the polyploid species are more numerous than the diploid species, perhaps due to the genetic diversity provided by the extra sets of chromosomes. The goal of this project is to first elucidate relationships among the diploid species in this group. Subsequently selected polyploid species will also be analyzed - each polyploid will contain genes from each of its parents, some of which are likely to be diagnostic, which will allow the identification of the hybridizing parents of each polyploid species. Ultimately these data will be used to address the classification of the species into taxonomic groups, to study the geographic patterns inherent in those relationships, and the evolution of morphological characters. The data to be employed in these analyses include nuclear ribosomal genes and chloroplast gene markers, as well as DNA sequences from nuclear-encoded genes of the alcohol dehydrogenase gene family. Molecular biology has provided researchers access to a wealth of genetic data, in particular DNA sequences, for analyzing relationships among species. Plant systematists have relied primarily on sequences from two sources: chloroplast DNA and nuclear ribosomal DNA, both of which are genetically tractable and easy to isolate. There is a vast resource of DNA sequences that have remained relatively untapped, however, in the rest of the plant nuclear genome. These types of sequences have been largely ignored by systematists primarily because they are more genetically complex and thus more difficult to isolate and characterize. This additional experimental effort, however, can be outweighed by the quantity and quality of data available from these sequences. Previous work by Dr. Randall Small on cotton and related species (genus Gossypium, also in the Mallow family) has shown that these types of sequences can be reliably isolated and can be exceptionally useful for systematic studies. These studies were expedited by the wealth of knowledge of cotton genetics because of its importance as a crop plant. To facilitate the transfer of such knowledge from well-known groups like Gossypium to less well characterized wild species groups (such as Hibiscus section Furcaria) the current project will use an understanding of the alcohol dehydrogenase gene family developed in Gossypium to address species relationships Hibiscus section Furcaria. Thus, this project provides a direct test of the transferability of information gleaned from a genetically well characterized group (Gossypium) to a less well understood group (Hibiscus section Furcaria).