Figure 1.—

Abortive gap-repair mechanism of internal deletion. (A) An intact TE construct consists, at the very least, of a transposase gene (Tr), a disease-resistance gene (R), and a pair of inverted repeats (IR) marking its boundaries. (B) Following transposition or deletion, a double-stranded gap is introduced into the host chromosome DNA. (C) This gap is sometimes filled by copying information from a homologous chromosome, sister chromatid, or ectopic chromosomal site containing the intact construct. (D) If this process is interrupted, then the central portions of the TE will not be copied. In some cases, this produces a dissociated construct not containing the resistance gene.