Figure 4.

Diagrammatic representation of integration of two copies of plasmid pWRG 2426 as direct repeats (A and B) or indirect repeats, with bar as two adjacent genes (C) or gusA as two adjacent genes (D) and the corresponding Southern hybridization band pattern after restriction digest of the genomic DNA with XbaI (X) or SacI (S) probed with bar (B), hpt (H), or gusA (G). The jagged lines represent intervening vector or plant DNA. It is assumed that the intervening DNA does not possess sites for XbaI and SacI. However, the altered band patterns can be predicted if sites for one or both enzymes are present. Although the sizes of the bands are arbitrarily represented as they would not be predictable, the bands of identical size for two or more genes represent the same fragment as shown by the horizontal lines between X or S for different arrangements. Following similar reasoning band patterns can be predicted for more than two copies.