Sequential chromosome banding and in situ hybridization analysis.

Different combinations of chromosome N- or C-banding with in situ hybridization (ISH) or genomic in situ hybridization (GISH) were sequentially performed on metaphase chromosomes of wheat. A modified N-banding-ISH/GISH sequential procedure gave best results. Similarly, a modified C-banding - ISH/GISH procedure also gave satisfactory results. The variation of the hot acid treatment in the standard chromosome N- or C-banding procedures was the major factor affecting the resolution of the subsequent ISH and GISH. By the sequential chromosome banding - ISH/GISH analysis, multicopy DNA sequences and the breakpoints of wheat-alien translocations were directly allocated to specific chromosomes of wheat. The sequential chromosome banding- ISH/GISH technique should be widely applicable in genome mapping, especially in cytogenetic and molecular mapping of heterochromatic and euchromatic regions of plant and animal chromosomes.