POWRE: Molecular Genetics of Ligule Development

这一POWRE奖项将允许Moreno博士完成她在玉米(Zea Mays)叶片发育方面的研究，这项工作是从博士后开始的，并重新确立了她作为独立研究员的地位。本研究项目的总体目标是了解玉米叶片的形成过程。叶舌是一组确定的细胞，在叶片形成过程中改变它们的极性和细胞分裂速度，形成铰链状结构。这一过程非常容易受到基因解剖和分子分析的影响，因为舌叶是可有可无的器官，可以通过对植物生存能力或繁殖力几乎没有影响的突变来完全消除。无叶舌1和无叶舌2基因的隐性突变在发育的非常早期就阻止了叶舌的形成。这个项目有明确的目标。第一种是通过插入突变对Liguleless1基因进行精细结构遗传分析，以确定是否有可能获得选择性地影响舌叶发育的各个方面或阶段的LG1突变。第二个目标是确定影响玉米舌状区的新突变。这项研究将集中在两类以前未描述的新突变的遗传和分子特征上。遗传力测试以及与野生型基因的显性关系将被确定。事实上，如果新的突变对应于新的基因座，将尝试分配染色体位置，并启动基因标记工作。最终的目标将是通过聚合酶链式反应辅助的定点突变来确定拟南芥中无配体2的同系物的结构和功能，以及可能的无配体1的同源物的结构和功能。通过DNA和蛋白质数据库的比较，可能的LG1和LG2类基因将被识别出来。这些基因的突变将解决单子叶和双子叶之间是否存在结构同源性的问题。

This POWRE award will allow Dr. Moreno to complete her research on leaf development in maize (Zea Mays), work begun as a postdoctoral student, and to re-establish herself as an independent investigator. The overall goal of this research project is to understand the process of ligule formation in maize. The ligule is a defined group of cells that change their polarity and their rates of cell division during leaf formation to form a hinge-like structure. This process is highly amenable to genetic dissection and molecular analysis because ligules are dispensable organs that can be completely abolished by mutations that have little effect on plant viability or fertility. Recessive mutations of the liguleless1 and liguleless2 genes block the formation of ligules at a very early time in development. This project has specific aims. The first is to perform a fine structure genetic analysis of the liguleless1 gene by insertional mutagenesis in order to establish whether or not it is possible to obtain lg1 mutations that selectively affect various aspects or stages of ligule development. The second goal is to identify new mutations that affect the ligular region of maize. This study will focus on the genetic and molecular characterization of two novel classes of previously undescribed mutations. Heritability tests as well as dominance relationships with the wild-type genes will be determined. If, in fact, the new mutations correspond to new loci, an attempt will be made to assign chromosomal location and gene-tagging efforts will be initiated. The final goal will be to determine the structure and function of the liguleless2, and possibly liguleless1, homologues in Arabidopsis by PCR-assisted site-selected mutagenesis. Through DNA and protein database comparisons, putative lg1- and lg2-like genes will be identified. Mutations in these genes will address the question of whether structural homologies exist between monocot and dicot leaves.