ABSTRACT
Fluorescence in situ hybridization is a very powerful technique for the detection of specific nucleic acid sequences and to localize highly repetitive DNA sequences in the specific regions of the chromosomes. Since the publication of Gall and Pardue, numerous modifications and refinements of techniques have facilitated the diagnosis and identification of chromosomal aberrations particularly for human and animal chromosomes. The application of an in situ hybridization technique in plants has lagged behind compared to its use in mammalian cytogenetics. The main handicap of utilizing this technique for plant chromosomes is to obtain a high frequency mitotic metaphase cells without cell wall and cytoplasmic debris. These obstacles hinder hybridization of low-copy-number sequences to the chromosomes. Genomic in situ hybridization (GISH) is a powerful cytological method to distinguish parental chromosomes or chromosome segments in an interspecific or intergeneric hybrids. In GISH, isolation the genomic DNA of the probe and blocking DNA should be free from contamination.
