Molecular Evolution and Systematic Applications of PGI Sequences in Plants

Clarkia属植物，原产于加州的一年生植物， 已经深入研究了其形态和 染色体来了解植物物种是如何起源的， 形态学和细胞学模式进化。 最近，博士。 位于戴维斯的加州大学的莱斯·戈特利布研究了 这些植物的生化和基因组方面来描述 他们的整体遗传差异的程度，以解释 特别的基因的进化，并学习如何使用它， 分子证据来推断 物种 许多种克拉氏菌都有重复的同工酶， 糖酵解酶磷酸葡萄糖异构酶（PGI），其催化 中间代谢的一个基本反应。 gottlieb博士 最近对编码这些同工酶的核基因进行了测序， 有无重复的物种。 出乎意料的是， 被证明有两种不同的结构，一种是大量的 外显子被不同长度的内含子分开， 完全没有内含子。 没有内含子的基因是 假设是从一个"加工"的基因， 当一个人的初级信使RNA转录本的拷贝 将结构化基因插入基因组中的一个位置， 这是一个可以表达的方向。 戈特利布博士将继续他的PGI基因分析 结构，以确定分类分布的 结构化和非结构化的PGI基因。 这又 将允许确定复制的来源， 与这些物种的生殖力相比， 其他形态学和分子学证据 研究 构成了最早的分子进化分析之一 野生（非栽培）植物中的核基因， 有关的组织和模式的描述， 序列变异是进化的源头

The plant genus Clarkia, of annuals native to California, has been investigated intensively for its morphology and its chromosomes to understand how plant species originate and how new morphological and cytological patterns evolve. More recently Dr. Les Gottlieb of the University of California at Davis has studied biochemical and genomic aspects of these plants to describe the extent of their overall genetic divergence, to account for the evolution of particular genes, and to learn how to use this molecular evidence to infer phylogenetic relationships among species. Many species of Clarkia have duplicated isozymes of the glycolytic enzyme phosphoglucose isomerase (PGI), which catalyzes an essential reaction in intermediary metabolism. Dr. Gottlieb recently sequenced the nuclear genes encoding these isozymes in species with and without the duplication. Unexpectedly the genes proved to have two different structures, one with a large number of exons separated by introns of varying lengths and the other with no introns at all. The genes without introns are hypothesized to be descended from a "processed" gene that arose when a copy of the primary messenger RNA transcript of a structured gene was inserted into the genome in a position and orientation that permitted it to be expressed. Dr. Gottlieb will continue his analysis of PGI gene structure in order to identify the taxonomic distribution of the structured and nonstructured PGI genes in Clarkia. In turn, this will allow determination of the origin(s) of the duplication when compared with the phylogeny of these species determined from other morphological and molecular evidence. The studies constitute one of the first analyses of molecular evolution in nuclear genes in wild (noncultivated) plants and are directly relevant to the description of the organization and pattern of sequence variation, the source of evolutionary change.