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Fig. 4 Evidence for transposition of the peach element by Southern blot analysis. Genomic DNA from lines 1085 (a), 1060 (b) and 1061 (c) were digested with BamHI (B), EcoRI (E), and SacI (S), and filters were probed with the 1.3-kb peach element from pWE1. If the peach element had integrated with flanking plasmid sequences, then digestion with EcoRI should generate a single 1.3-kb band, and digestion with SacI, which recognizes one site in the peach element and one in the multicloning site of pWE1, should produce a fragment of 800 bp and a second fragment with a size dependent upon the site of integration. However, the hybridization patterns for the three samples differ, and the fragments are much larger than expected. These findings indicate that integration of the peach element occurred without flanking plasmid sequences and that the genomic sites of integration are different. (Molecular weight standards are shown to the left. The arrow indicates the location of the intact 1.3-kb peach element from pWE1 following digestion with EcoRI.)