Fig. 2. Binary vector/helper transposon transformation system. (A) Active transposons are mobile elements that consist of two inverted terminal repeats (black) that flank an open reading frame encoding a transposase. Both features are required for transposition. The inverted repeats are commonly called 5' or Left (L) and 3' or Right (R). Transposition results in a duplication of the insertion site (blue). (B) Transposon and transposase can be separated, resulting in a binary vector/helper transposon transformation system that allows the regulated transposition of transgenes into the genome. Transposition events are identified by dominant markers (green, and see Table 2 and Box 3).