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

[9972647] baum and Hileman最近的研究集中在模式植物系统上，包括金鱼草（金鱼草科），已经发现了影响花发育、花形和花部分的单个基因。研究生Lena Hileman在哈佛大学David Baum博士的指导下，正在研究金鱼龙的近亲Mohavea属和Sairocarpus属，以构建该物种的分子系统发育（主要基于叶绿体ndhF序列），以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龙花产生的四个雄蕊的基因。研究这种差异的遗传基础是由于在金鱼龙中发现了一个影响雄蕊败育的基因CYCLOIDEA （CYC）。在snapdragon中，CYC在五个雄蕊原基中的一个中表达，并导致雄蕊流产（留下四个雄蕊成熟）。cyc样基因在四倍体Mohavea（可能有多个拷贝）中的表达将在组织准备中进行研究，以观察这些基因是否在三个流产雄蕊的早期阶段表达。本研究对玄参科植物的花性状发育控制进行了精细的遗传解剖，用于种级和属级分类。由于Mohavea植物是四倍体（包含两个完整的基因组），因此它们预计具有两个CYC拷贝和两个密切相关的基因DICHOTOMA （DICH）拷贝。该项目将包括CYC/DICH基因家族成员的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更强的自然选择的影响（正如分子进化速度降低所表明的那样）。通过对这些基因的选择性历史的详细了解与基因表达模式的研究，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。

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.