Springer 9712927 A transposon tagging system has been established using Ds transposable elements containing reporter genes. A collection of lines, each containing a Ds element inserted randomly in the Arabidopsis genome, has been generated. The Ds element carries a reporter gene, allowing the expression pattern of nearby genes to be monitored via the reporter gene. These lines have been screened for reporter gene expression in the shoot apex of Arabidopsis seedlings. Several genes have been identified that are specifically expressed in discrete domains within the shoot apex. These include genes expressed specifically in the shoot apical meristem, and genes expressed in domains at the base of each leaf primordium. Two lines (GT185 and GT522) have been chosen for further characterization. These lines both exhibit expression of the reporter gene in a group of cells subtending each organ (rosette leaf, cauline leaf, flower) and organ primordium. The expression pattern suggests that the genes controlling the reporter gene may be involved in the establishment of a boundary between the shoot apical meristem and organ primordia. As a first step in the characterization of the genes controlling reporter gene expression in these two lines, the reporter gene expression pattern will be carefully analyzed at different developmental stages. The genes controlling reporter gene expression will be cloned by amplification of DNA flanking the Ds insertion. The genes will be molecularly characterized by sequencing and in-situ hybridization. The relationship between GT185, GT522 and two genes that have previously been shown to play a role in meristem function will be examined.
