PCR analysis for site-specific recombination and the presence of the recombinase gene the manual cross (MC
) generation. PCR reactions (a, c) with primers eand for (b, d) with primers gand hon representative plant DNAs. a, b) Segregated lines (lanes 1, 2) S1-Bxb1.9; (lanes 3, 4) S1-Bxb1.12; (lane 5, 6) S1-Bxb1.35; (lane 7, 8) S1-Bxb1.28 negative for excised target but positive for Bxb1 gene. As target line TA3-Bxb1.28 appears to be homozygous no Bxb1 expression lines were derived from the retransformation event. c, d) MC1-Bxb1.9.31 with predicted, excision events (0.43 kb) only appearing in lanes when the recombinase gene is present (0.72 kb). Control lanes are B (blank, no DNA); E (excision, pN6-Bxb1exc DNA); N (no excision, pN6-Bxb1); P (pCOXS3-Bxb1).