Analysis by Transposon Display of the behavior of the dTph1 element family during ontogeny and inbreeding of Petunia hybrida

Transposon Display is a high-resolution method that was used here to visualize simultaneously individual members of the dTph1 transposable element family of Petunia hybrida. The method provides a tool for accurate analyses of copy numbers and insertion frequencies, and a means to study the behavior of a family of elements as a whole. Somatic insertion events can be identified and insertion events in a cell of the L2 apical lineage can be distinguished unequivocally from those in a cell outside this lineage. In sublines of the high-copy-number line W137, an average insertion rate equivalent to transposition of 10% of the total number of element copies in each generation was measured, copy number increases of over 20% in four generations were recorded, and element position turnover was analyzed. Insertion events are detected essentially randomly both in time and space. The general applicability of the technique for the analysis of the transpositional behavior of element systems is discussed.