Apical meristems are responsible for the production of the entire postembryonic plant, aerial and subterranean. The sites at which meristems are initiated, and their patterns of development, growth, and arrest are responsible for the establishment of the architectural patterns of the shoot and root systems. These architectural patterns contribute to the overall light harvesting efficiency, water and nutrient absorption, and productivity of the plant. For these reasons, and for gaining increased understanding of basic plant developmental processes, it is important to analyze the ways in which meristems are initiated, organized, and function. The experiments that Dr. Sussex will carry out are based on the assumption that the initiation and organization of lateral root meristems represents a developmental pathway consisting of a sequence of genetically controlled molecular and cellular events. The experiments are designed to dissect this pathway in the following ways. First, he will define cellular events that occur early in lateral root meristem formation, including the contribution of cell cycle events and the role of cortical microtubule arrays; second, he will analyze the regulation of genes that are expressed during initiation and early development of lateral root meristems; third, he will isolate, map, and analyze mutants in lateral root meristem initiation and organization, and order the pathway into a temporal sequence. He will relate the cellular and molecular aspects of lateral root development genetically by comparing them in wild type and in mutants for lateral root development, and experimentally by uncoupling lateral root development from cell division and DNA replication.
