AN ARABIDOPSIS-THALIANA RFLP MAPPING SET TO LOCALIZE MUTATIONS TO CHROMOSOMAL REGIONS

Mapping of newly identified Arabidopsis thaliana mutants is an importa nt step towards their molecular characterization and the attempt to sa turate the genome by known mutations. The classical genetic analysis u sing phenotypic tester lines is well-established, but laborious, time- consuming and potentially ambiguous. An alternative molecular strategy was developed that is based on RFLPs. Subcloned DNA markers that dete ct only segregating RFLP bands distinguishing A. thaliana ecotype Land sberg from Columbia or Enkheim after EcoRI restriction digestion compo se an Arabidopsis RFLP mapping set (ARMS). Up to 13 markers uniformly cover the five A. thaliana chromosomes and can be scored in only two s uccessive Southern experiments on a single blot without mutual interfe rence of the signals. Thus, this system allows a simple, reliable, rap id and especially inexpensive mapping of any monogenic mutant locus to the A. thaliana chromosomes. Several loci can be analysed in one expe riment if the respective blots are hybridized together. This paper dem onstrates the mapping of two recessive mutants affecting the developme nt of A. thaliana leaves which had been generated in the Columbia and Enkheim ecotype by analysing less than 20 F2 individuals. Further mark ers to refine or verify the result on the same blot can be chosen out of 14 additional probes detecting single segregating EcoRI polymorphic bands as well.