Ds elements on all five Arabidopsis chromosomes and assessment of their utility for transposon tagging

The maize transposons Activator (Ac) and Dissociation (Ds) tend to transpose to sites close to their original position and can be efficiently used to transposon-tag genetically linked genes. To facilitate this approach, we describe the locations of seven T-DNAs carrying Ds elements, including at least one on each of the five chromosomes. For five of these T-DNAs, we have confirmed that the Ds element transposes preferentially to genetically linked sites. A large-scale transposon-tagging experiment was performed by activating Ds from eight chromosomal locations that included at least one on each of the five chromosomes. These experiments produced a total of 1132 F-3 families that were predicted to carry around 870 independent Ds insertions. In these populations, 33 independently isolated mutants that were visibly different from wild-type were identified. Twenty-nine of these mutants were studied genetically, and 14 were not tagged with Ds because the element could be separated from the mutation by recombination. The remaining 15 mutations were possibly tagged because the transposon and the mutation were not separated by recombination. These experiments provide tools for transposon-tagging on each chromosome, and indicate that approximately 50% of identified mutations are likely to be tagged, thereby enabling cloning of the affected genes.