Ray 9630402 The integrity, as well as the diversity of chromosomes, is maintained by recombination and yet little is known about how this mechanism is judiciously performed, particularly in plants. A system of induced mitotic recombination in Arabidopsis thaliana, in which a single, defined, DNA double strand break is delivered to the chromosome at a particular locus has been developed. The target site of a site-specific DNA endonuclease, HO endonuclease of yeast, is cloned into a unique chromosomal location and the break induced by the expression of a cloned HO gene in the plant. Specific objectives are 1) to test the hypothesis that a chromosomal double strand break in meiosis can induce homologous recombination in Arabidopsis and 2) to determine whether ectopic recombination can be stimulated in mitosis and meiosis by a DNA double strand break in the plant chromosome. %%% A better understanding of the basic mechanisms involved in recombination of plant chromosomes will result from this study using the model plant, Arabidopsis thalania. Moreover, any movement toward the goal of achieving site-specific recombination in plants will have significant impact in both basic and applied research.
