Squash dot hybridization
The in-situ hybridization technique is often used for locating the position of the repeat sequence (including sat-DNA) on a specific chromosome. However, in some cases the repeated DNA from an alien species is used for detecting the presence of chromatin material introduced from this species in a crop plant due to introgression. Sometimes, a cytogeneticist may need to screen large population of a crop species to select plants that may carry alien genetic material. Squash dot hybridization technique is designed for this purpose. In this technique one root tip from a germinated seed may be squashed onto nitrocellulose filter and the filters are hybridized with radioactively labelled repeated DNA probe derived from the alien species in question.