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Home >>Molecular Maps of Plant Genome >>Identification of Breeding Lines and Varieties Using RFLPs
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Identification of Breeding Lines and Varieties Using RFLPs - It has been demonstrated that even closely related individuals of some species (e.g. humans) can be distinguished using DNA fingerprinting. Although probes equivalent in resolution to minisatellite or VNTRs of human beings have not been reported in plants, genotype specific RFLP patterns have been detected and based for the identification of breeding lines and varieties and also for the characterization of germplasm resources.

DNA fingerprinting, using simple sequence repeats or oligonucleotides, ego (CT)n or (AC)n, has also been utilized in plants. Genotype specific RFLP patterns have already been detected and their use for distinguishing varieties has been suggested in crops like maize, oilseed, lettuce, soybean, potato and rice.

An exception, however, may be tomato, where intervarietal differences were rare. In rice, cultivar specific DNA fingerprints were obtained when a human minisatellite DNA probe was used. Any character, used for variety identification needs to fulfill the following basic criteria:
(i) distinguishable intervarietal variation,
(ii) minimal intarvarietal variation,
(iii) environmental stability and
(iv) experimental reproducibility (in cases of biochemical or molecular markers): These requirements are met in most of the cases where molecular markers have been identified for the detection of varieties.

In barley, cDNA clones for hordein proteins were used to demonstrate that polymorphism exists for RFLPs in several barley cultivars which can therefore be identified using RFLPs. In j1otato, two probe/enzyme combinations were found adequate for the identification of more than 100 varieties, and one probe/enzyme combination distinguished 19 out of 20 4x' varieties and 33 out of 38 2x lines.

However, the limitations for the practical use of RFLPs for variety identification include the following:
(i) use of radioactive isotope is inconvenient,
(ii) the technique is expensive, and
(iii) the technique is labour intensive. As already discussed, non- radioactive labelling (biotin and digoxigenin) has already become possible for use of molecular probes.
Similarly, automization (use of automatic equipments, reducing dependence on labour) and standardization of the technique will make it less expensive and less labour intensive, so that the RFLP fingerprint technology will develop into a valuable and reliable varietal diagnosis tool.

 
 

 

 
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