Telomeres are the specialized structures that form the termini of eukaryotic chromosomes. These structures are essential for the replication and maintenance of the genome. Telomeres have been extensively studied in lower eukaryotes but considerably less in known about higher eukaryotic telomeres. A higher eukaryotic telomere has recently been cloned from the flowering plant Arabidopsis thaliana, providing the opportunity to study the telomeric regions of this organism as a model system. Two aspects of telomere structure and function will be studied. First, the nature and organization of the DNA sequences that lie adjacent to A. thaliana telomeres will be investigated. Second, the mechanism by which a broken chromosome end acquires a new telomere (i.e., telomere healing) will be studied using a chromosomal mutant of A. thaliana which carries a healed telomere. The healed telomere will be isolated and its structure compared to that of the original chromosomal site to determine how the healing event took place. In addition, the healed telomere, which resided proximal to a centromere, will be investigated as a potential tool for studying A. thaliana centromere structure. Characterization of essential structural components of chromosomes gives greater insight into a basic understanding of mechanisms used by cells to maintain the correct chromosome complement. Additionally, this information could be useful in engineering artificial chromosomes for plants, a technique which would add significantly to the already powerful repertoire of available molecular techniques.
