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.
