Cytological Characterization of Somatic Hybrids: Detection of Genome Origin by Genomic In Situ Hybridization (GISH)

Genomic in situ hybridization (GISH) allows genomes differing in molecular composition to be discriminated visually in cell nuclei. Total genomic DNA from a given genotype (e.g. AA) is used to probe for chromosomes of A in hybrids (e.g. AB; Plate 1 b, c), allopolyploids (e.g. AABB; Bennett et al. 1992; Kenton et al. 1993b; Leggett and Markhand 1995), or lines of B introgressed with DNA from A (Mukai et al. 1993a; Parokonny and Kenton 1995). The hybridization target is chromosomal DNA in spreads (Plate 1 b, c), sections (Leitch et al. 1990) or whole, isolated nuclei (van Dekken et al. 1989). The last two examples are useful for studying genome domains in hybrid nuclei, a major application of GISH (Schwarzacher et al. 1989; Leitch et al. 1990).