Molecular Studies of PgiC Evolution in Allotetraploid Species of Clarkia (Onagraceae)

克拉克亚（Onagraceae）异源四倍体物种 PgiC 进化的分子研究

• 批准号: 9615037
• 负责人: Leslie Gottlieb
• 金额: $ 15万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-15 至 2001-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9615037&HistoricalAwards=false
• 关键词: Molecular; Studies; PgiC; Evolution; Allotetraploid

9615037 Gottlieb The genus Clarkia of the evening-primrose family (Onagraceae) is a group of 42 species, all but one native to western North America, that has been examined for more than 50 years as a model for understanding speciation and genetic divergence and to assess the value of different sources of evidence for inferring phylogeny. The genealogical relationships among the species have been resolved by analyses of many classes of characters, including nucleotide sequences of the gene PgiC which encodes the cytosolic isozyme of phosphoglucose isomerase, an essential enzyme of sugar metabolism in plants. PgiC was duplicated in the basal stock that gave rise to Clarkia, and about half the extant diploid species express both duplicated genes (have two PgiC isozymes). In the other diploid species, one PgiC gene has been "silenced" (there is only one isozyme present for enzyme function, but there are two detectable DNA loci). Clarkia also includes a number of allotetraploid species, that combine through hybridization the genomes (chromosome sets) of two diploid species and are thus expected to possess four PgiC genes. However, in all tetraploid Clarkias tested only two PgiC genes have been found. The major goal of Prof. Gottlieb's research is to determine through DNA nucleotide sequencing which PgiC genes are expressed and whether the genes that are not expressed have been mutated or lost. In this study, the naturally occurring tetraploid species will be compared to experimentally synthesized hybrids between their diploid progenitors. In addition, hybrids between the diploids and tetraploids will be studied. The synthesized hybrids are expected to express all the PgiC genes of their parents. The extent and rate of nucleotide divergence between the duplicate genes will be compared between the diploid and tetraploid genomes. The proposed studies are an attempt to describe at the molecular level the fate of particular genes encoding enzymes of known function during the formation and establishm ent of allotetraploid plant species. Such basic information should also help guide future analysis of the molecular causes of gene silencing and loss. The study will also provide information about the use of nuclear genes from polyploids in analyzing phylogeny, a highly relevant issue in plant systematics because more than half of the flowering plants are polyploid.

小行星9615037 晚报春花科（Onagraceae）的属Clarkia是一组42种，除了一个原产于北美西部，已被研究了50多年，作为了解物种形成和遗传分化的模型，并评估推断物种发生的不同证据来源的价值。通过分析许多种类的性状，包括编码磷酸葡萄糖异构酶（植物糖代谢的必需酶）的胞质同工酶的基因PgiC的核苷酸序列，已经解决了物种之间的亲缘关系。PgiC在产生Clarkia的基础原种中复制，并且大约一半的现存二倍体物种表达两种复制的基因（具有两种PgiC同工酶）。在其他二倍体物种中，一个PgiC基因被“沉默”（只有一种同工酶存在于酶功能中，但有两个可检测的DNA基因座）。Clarkia还包括许多异源四倍体物种，其通过杂交将两个二倍体物种的基因组（染色体组）联合收割机组合，因此预期具有四个PgiC基因。然而，在所有四倍体Clarkias中，只发现了两个PgiC基因。Gottlieb教授的研究的主要目标是通过DNA核苷酸测序确定哪些PgiC基因表达，以及不表达的基因是否已经突变或丢失。 在这项研究中，自然发生的四倍体物种将进行比较，实验合成的杂种之间的二倍体祖先。此外，还将研究二倍体和四倍体之间的杂交。预期合成的杂交体表达其亲本的所有PgiC基因。将在二倍体和四倍体基因组之间比较重复基因之间的核苷酸分歧的程度和速率。这些研究试图在分子水平上描述异源四倍体植物物种形成和建立过程中编码已知功能酶的特定基因的命运。这些基本信息也有助于指导未来对基因沉默和缺失的分子原因的分析。这项研究还将提供有关使用多倍体细胞核基因分析植物发生的信息，这是植物系统学中一个高度相关的问题，因为一半以上的开花植物是多倍体。