Dissertation Research: The Role of Floral Symmetry Genes in the Evolution of Stamen Development in Mohavea (Scrophulariaceae, Antirrhineae)

论文研究：花对称基因在莫哈维（玄参科、金鱼科）雄蕊发育进化中的作用

• 批准号: 9972647
• 负责人: Elena Kramer
• 金额: $ 0.94万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2002-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9972647&HistoricalAwards=false
• 关键词: Dissertation; Research; Role; Floral; Symmetry

9972647Baum and Hileman Recent studies focusing on model plant systems including the snapdragon Antirrhinum majus (family Scrophulariaceae) have identified individual genes affecting flower development, floral shape, and floral parts. Graduate student Lena Hileman, under the direction of Dr. David Baum at Harvard University, is investigating close relatives of the snapdragon in the genera Mohavea and Sairocarpus, to construct a molecular phylogeny of the species (mostly based on chloroplast ndhF sequences) in order to explore evolutionary changes in the floral development genes. The specific aim is to determine the genes that cause Mohavea flowers to have only two stamens as opposed to the four produced by snapdragon flowers. The search for the genetic basis of this difference is facilitated because a gene influencing stamen abortion, CYCLOIDEA (CYC), has been characterized in snapdragon. In snapdragon, CYC is expressed in one of the five stamen primordia and results in that stamen aborting (leaving four stamens to mature). Expression of CYC-like genes in the tetraploid Mohavea (where there may be multiple copies) will be studied in tissue preparations to see if these genes are expressed in early stages of the three aborted stamens. The work constitutes a fine-scale genetic dissection of the developmental control of floral characters used in the species- and genus-level classification of Scrophulariaceae plants. Because plants of Mohavea are tetraploid (contain two complete genomes), they are expected to possess two copies of CYC and two copies of a closely related gene, DICHOTOMA (DICH). The project will include DNA sequencing of the members of the CYC/DICH gene family in order to provide information regarding molecular evolutionary changes in this gene family. Preliminary work has already identified four potential gene products, thus providing material for sequence analysis to determine whether some of the genes have been subject to stronger natural selection (as indicated by reduced rates of molecular evolution). By combining a detailed understanding of the selective history of these genes with studies of gene expression patterns, we will learn about the fate of duplicate genes during genome evolution and their role in morphological diversification.

9972647Baum 和 Hileman 最近针对包括金鱼草金鱼草（玄参科）在内的模型植物系统的研究已经确定了影响花发育、花形状和花部分的个体基因。 研究生 Lena Hileman 在哈佛大学 David Baum 博士的指导下，正在研究 Mohavea 属和 Sairocarpus 属中金鱼草的近亲，以构建该物种的分子系统发育（主要基于叶绿体 ndhF 序列），以便探索花发育基因的进化变化。具体目标是确定导致莫哈维花只有两个雄蕊而不是金鱼草花有四个雄蕊的基因。 由于金鱼草中影响雄蕊败育的基因 CYCLOIDEA (CYC) 已得到表征，因此有助于寻找这种差异的遗传基础。 在金鱼草中，CYC 在五个雄蕊原基之一中表达，并导致该雄蕊败育（留下四个雄蕊成熟）。将在组织制剂中研究CYC样基因在四倍体Mohavea（可能有多个拷贝）中的表达，以观察这些基因是否在三个败育雄蕊的早期阶段表达。这项工作对用于玄参科植物的种和属水平分类的花性状的发育控制进行了精细的遗传剖析。 由于 Mohavea 植物是四倍体（包含两个完整的基因组），因此预计它们拥有两个 CYC 拷贝和两个密切相关的基因 DICHOTOMA (DICH) 拷贝。该项目将对 CYC/DICH 基因家族成员进行 DNA 测序，以提供有关该基因家族分子进化变化的信息。初步工作已经确定了四种潜在的基因产物，从而为序列分析提供了材料，以确定某些基因是否受到了更强的自然选择（如分子进化速率降低所示）。通过将对这些基因的选择历史的详细了解与对基因表达模式的研究相结合，我们将了解基因组进化过程中重复基因的命运及其在形态多样化中的作用。