AFLP Analysis
AFLP, or Amplified Fragment Length Polymorphism, is a DNA fingerprinting technique which detects multiple DNA restriction fragments by means of PCR amplification. The AFLP technology usually comprises of the following steps:
•the restriction of the DNA with two restriction enzymes, preferably a hexa-cutter and a tetra-cutter;
•the ligation of double-stranded adapters to the ends of the restriction fragments;
•the amplification of a subset of the restriction fragments using two primers complementary to the adapter and restriction site sequences, and extended at their 3' ends by "selective" nucleotides (Figures 1 and 2);
•gel electrophoresis of the amplified restriction fragments on denaturing slab gels or capillaries;
•the visualization of the DNA fingerprints by means of auto-radiography, phospho-imaging, or other methods.
The amplification primers, known as AFLP primers, are generally 17 - 21 nucleotides in length and anneal perfectly to their target sequences; i.e. the adapter and restriction sites, and a small number of nucleotides adjacent to the restriction sites (Figure 2). This renders AFLP a very reliable and robust technique, which is unaffected by small variations in amplification parameters (e.g. thermal cyclers, template concentration, PCR cycle profile).