Diploid and Polyploid Hybridity Throughout the Evolutionary History of Glycine (Leguminosae)

尽管豆科植物甘氨酸属包括栽培大豆（g.m ax），但其进化史和分类关系仍有待研究。其中包括与古代基因组重复事件相关的整个属的起源，该属大约25个二倍体多年生物种所属的生殖隔离“基因组群”之间的关系，以及这些基因组群中密切相关物种之间遗传分化的复杂历史。所有这些问题都有一个共同的可能性，即杂交在产生从核、叶绿体和线粒体基因中观察到的DNA变异模式中发挥了作用。多倍体（多组染色体）和异体多倍体中的杂交是形成植物基因组的两个最重要的过程，包括小麦、玉米、棉花和大豆等栽培植物。在甘氨酸的例子中，杂交是否参与了多倍体的形成尚不清楚，假设发生在1500万年前，如果是这样，什么物种是这两个基因组的供体。通过研究不同染色体或不同基因组区室（线粒体、叶绿体）上的大量基因，可以解决这个问题以及甘氨酸历史中涉及多倍体和杂交作用的其他问题。这些基因的最大来源是核基因组，该项目利用大豆和其他豆类（如苜蓿）的基因组项目提供许多候选基因供研究。将评估大约100个核基因在解决系统发育问题方面的效用，同时考虑到诸如在大豆遗传图谱上的位置等附加标准。分析方法将包括使用各种方法重建系统发育，评估不一致性，测试多裂和杂交，网络构建和混合评估。这项工作将解决一般问题，处理不一致，识别和使用低拷贝核基因，并研究多倍体。由于多倍体和杂交现象普遍存在，因此更好地了解多倍体和杂交现象，特别是甘氨酸的多倍体和杂交现象，对植物生物学和遗传学具有广泛的相关性和意义。该项目将对科学基础设施产生影响，培养本科生、研究生和一名博士后，包括少数民族本科生，他们将参加暑期研究实习。与康奈尔大学生物教师研究所的合作将为高中和初中学生开发系统发育实验室。该项目的范围是国际性的，有来自美国和澳大利亚的研究人员参与，涉及在两国以甘氨酸种子收集的形式利用和增强种质资源。

Despite the fact that the legume genus Glycine includes the cultivated soybean (G. max), much remains to be learned about its evolutionary history and taxonomic relationships. These include the origin of the entire genus associated with an ancient genome duplication event, relationships among the reproductively isolated "genome groups" to which the approximately 25 diploid perennial species of the genus belong, and the complex history of genetic differentiation among closely related species within these genome groups. All of these issues have in common the possibility that hybridization has played a role in producing the patterns observed in DNA variation from nuclear, chloroplast, and mitochondrial genes. Polyploidy (multiple sets of chromosomes) and hybridization separately, or together in allopolyploidy, are two of the most important processes that shape the genomes of plants, including cultivated plants such as wheat, maize, cotton, and soybean. In the case of Glycine it is unknown whether hybridization was involved in polyploid formation, as hypothesized to have occurred 15 million years ago, and if so, what species were the donors of the two genomes. This and other questions at progressively more recent stages in the history of Glycine that involve the role of polyploidy and hybridization can be addressed by studying a large number of genes on the different chromosomes or in different genomic compartments (mitochondrion, chloroplast). The largest source of such genes is the nuclear genome, and this project taps genomic projects in soybean and other legumes (e.g., Medicago truncatula) to provide many candidate genes for study. Around 100 nuclear genes will be assessed for their utility in addressing phylogenetic questions, taking into account such additional criteria as position on the soybean genetic map. Analytical methods will include phylogeny reconstruction using various approaches, assessment of incongruence, testing for polytomies and hybridity, network construction, and admixture assessment. The work will address general issues of dealing with incongruence, identifying and using low copy nuclear genes, and studying polyploidy. Achieving a better understanding of polyploidy and hybridization in general, and particularly in Glycine, is of broad relevance and significance for plant biology and genetics because of the prevalence of these phenomena. The project will have an impact on the infrastructure of science by training undergraduate and graduate students and a postdoctoral fellow, including minority undergraduate students who will participate in summer research internships. Collaboration with the Cornell Institute for Biology Teachers will lead to the development of phylogeny laboratories for high school and middle school students. The project is international in its scope, with researchers from the United States and Australia, and involves the use and enhancement of germplasm resources in the form of Glycine seed collections in both countries.