PGI Gene Sequences and Phylogenetic Inferences in Clarkia

Clarkia 的 PGI 基因序列和系统发育推断

• 批准号: 9106831
• 负责人: Leslie Gottlieb
• 金额: $ 21.3万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-01-01 至 1995-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9106831&HistoricalAwards=false
• 关键词: PGI; Gene; Sequences; Phylogenetic; Inferences

Evolutionary Biology has been studied in the California annual plant Clarkia (Onagraceae) for four decades and the genus has provided a number of model systems in which to study the origin of species, genetic variation in natural populations and, more recently, molecular evolution. The molecular studies were initiated to determine the mode of origin of the duplicated cytosolic phosphoglucose isomerase (PGI) siozymes that are present in 12 Clarkia species but absent in 12 others. PGI catalyzes an essential reaction in sugar metabolism. To date, several PGI genes have been partially sequenced. They have remarkably complex structure with 19 exons (and 18 introns) so far identified encoding about 88% of the PGI protein (483/550 amino acids), the largest number of exons known for any plant gene. A gene encoding the chloroplast PGI isozyme from a different Clarkia has also been sequenced; it has a continuous open reading frame with no exons. During the current project, additional PGI genes encoding both isozymes from clarkias with and without the duplication will be cloned and sequenced. Evidence from the sequences will be used to determine whether the duplication occurred early in the evolution of genus and was retained in some lineages but lost in others or whether it arose more recently. Since duplicated PGIs characterize species in four taxonomic sections but are absent in three other sections, the evidence can be expected to resolve the phylogenetic relationships among the sections, a problem that has remained refractory even though Clarkia has been studied intensively. The sequence evidence will also be used to compare the rate and amount of divergence between the plastid and cytosolic PGIs. The analysis will contribute to understanding the mechanisms that generate molecular divergence and constitutes one of the few studies to date of the evolution of plant nuclear genes encoding proteins.

进化生物学在加州一年生植物Clarkia(Onagraceae)中已经研究了40年，该属提供了许多模式系统来研究物种的起源、自然种群中的遗传变异以及最近的分子进化。分子研究是为了确定复制的胞质磷酸葡萄糖异构酶(PGI)siozyme的来源模式，该酶存在于12个克拉基属物种中，但在其他12个物种中不存在。PGI催化糖代谢中的一个重要反应。到目前为止，已经对几个PGI基因进行了部分测序。它们具有非常复杂的结构，有19个外显子(和18个内含子)，编码约88%的PGI蛋白(483/550个氨基酸)，是已知的植物基因中数量最多的外显子。来自不同克拉克藻的一个编码叶绿体PGI同工酶的基因也被测序；它有一个连续的开放阅读框架，没有外显子。在目前的项目中，将克隆和测序其他编码Carkias和Carkias两种同工酶的PGI基因。来自序列的证据将被用来确定这种复制是发生在属的进化早期，并在一些谱系中保留，但在另一些谱系中消失，还是最近才出现。由于重复的PGI在四个分类组中描述了物种，但在其他三个组中没有，因此可以预期这些证据将解决这些组之间的系统发育关系，这一问题仍然是一个棘手的问题，尽管已对克拉克纲进行了深入的研究。序列证据也将被用来比较叶绿体和细胞质PGI之间的分化速度和数量。这一分析将有助于理解产生分子差异的机制，并构成迄今为数不多的植物核基因编码蛋白质进化的研究之一。