Arabidopsis thaliana is a weed, a member of the mustard family. In contrast to other plants which have been characterized at the molecular level, Arabidopsis has a small genome, very little repetitive DNA, primarily single copy genes and a relatively short life cycle. Thus, for a plant, it is ideally suited for genetic and molecular studies. Two independent projects are proposed here, both aimed toward an understanding of the genetic processes of the flowering plant Arabidopsis thaliana. The first project involves development and use of a genetic selection for trans-acting regulatory mutations that reduce or eliminate expression from one or both of two different embryo-specific gene promoters. When such mutations are obtained they will be studied both at the genetic and molecular level. The second project is the study of a series of Arabidopsis mutations that cause homeotic transformations of floral organs. These studies involve the genetic characterization of mutations that are already known, isolation of new mutations, and molecular cloning of one or more of the genes responsible for these mutations. The goal of the first project is to understand the mechanism of tissue specific gene expression and the second to understand pattern formation in morphogenesis at a molecular level. Plants offer unique advantages for understanding the genetically imprinted program of development which leads to a mature organism but such studies cannot be done in most plants because of genome complexity and size. Arabidopsis as are experimental system offers the advantages of plants without the disadvantages. The successful completion of these projects by Dr. Meyerowitz and his associates could not only produce significant information but provide an experimental system equalled only by Drosophila melanograster for the exploration of developmental genetics.
