DNA
Fingerprinting - A DNA fingerprint of an individual is prepared by digesting its DNA with a restriction enzyme, subjecting the DNA digest to electrophoresis and Southern hybridization with a probe specific for a highly variable region so that a large amount of polymorphism is generated. In case of human beings, minisatellite DNAs are used as probes, but such probes are not available for plants.
Therefore, RFLPs are commonly used for identification of commercial varieties, characterization of germplasm lines, etc. DNA fingerprints are also prepared by using as probes simple sequence repeat oligonucleotides like (CT)n or (AC)m and even human minisatellite DNA, e.g., in rice. In potato, for example, a two probe/enzyme combination for producing RFLPs was able to distinguish more than 100 varieties.
Thus for varietal identification it may often be necessary to use two or more restriction enzymes and probes. But in some crop plants like tomato, cultivars may show infrequent polymorphism preventing the use of RFLPs for varietal identification.
