Restriction Fragment Length Polymorphism

• Restriction fragment length polymorphism (abbreviated RFLP) refers to differences (or variations) among people in their DNA sequences at sites recognized by restriction enzymes.
• Such variation results in different sized (or length) DNA fragments produced by digesting the DNA with a restriction enzyme.

Procedure for Studying RFLPS

• Larger molecular weight genomic DNAs are isolated from related species.
• Each DNA is then digested with the same selected restriction enzyme.
• The fragments in these digests are separated by gel electrophoresis.
• The resulting gel lanes are denatured and transferred to a suitable solid support. Eg: Nitrocellulose filter membrane, and the DNA fragments are fixed to it firmly.
• The filter is hybridized with the appropriate radioactive single stranded DNA probe (Southern hybridization) and free probe are washed off.
• The band with which the selected probe has hybridized are detected by auto radiography.

Importance of RFLP maps 

• Identification and isolation of any gene linked with known RFLP loci.
• Unequivocal identification of strains/varieties.
• Linkage mapping of quantitative loci (QTL).
• Indirect selection for QTL tightly linked with RFLP loci.