Abstract: This invention relates to improved methods for transposon tagging as a route to plant gene isolation. The specific improvements comprise efficient means for preselecting plants which have undergone transposition. Through use of this preselection, it is possible to substantially reduce the number of plants which must be inspected to locate individuals having the transposon excised and inserted into a gene of interest. The result is a substantial savings in time, costs and efficiency associated with growing and screening large numbers of plants for tagging and isolation of a desired plant gene.