The apical and root meristem are the most important structures of the plant embryo responsible for further development. These meristems give rise to the aerial and underground portions of the mature plant. Two aspects of apical meristem development are central to its function. First, the apical meristem must maintain a pool of proliferating, undifferentiated cells. This pool continually provides new cells for organ generation. Equally important is maintaining the balance between the proliferation of the meristem cells and their subsequent differentiation. As meristem cells become distal to the apical meristem tip as a result of cell division, these distal cells must be allowed to enter a specific developmental pathway leading to eventual differentiation. Thus the apical meristem can be thought of as having two zones, a central zone containing meristem cells in an undifferentiated state (or uninduced towards a differentiated state), and a surrounding peripheral zone where cells are entering a specific developmental pathway toward a differentiated state. As a first step toward determining the genes controlling meristem development, mutations with defects in these two processes must be identified. CLV1 mutants develop excess undifferentiated meristem cells and may be required to maintain the balance between cell proliferation and cell differentiation in the meristem. Two other loci, CLV2 and CLV3, also appear to be involved in the same process based on their similar phenotype. This investigator proposed to investigate meristem development by addressing several questions: (1) What is the gene product encoded by the CLV1 locus; and does this give any clues to its function?; (2) What is the mRNA expression pattern for CLV1?; (3) Does CLV2 function in the same pathway as CLV1 and CLV3, and is there any evidence for direct interactions between these loci?; and (4) Are there other genes that interact with CLV1 and CLV3? These studies should provide exciting n ew information about some of the genes and processes involved in meristem development.
