This is based on the probability that a given DNA sequence (complementary to that of the primer) will occur in the genome, on opposite DNA strands, in opposite orientation, within a reasonable distance amplifiable by PCR.
For most plant materials, primers that are 9-10 nucleotides long (random sequences with at least 50% G and C and lacking inverted repeats) are predicted to generate, on an average, 2-10 amplification products. Polymorphism results mainly due to changes in the primer binding site's presence or absence, and amplification products represent one allele per locus.
The use of PCR technology for preparation of genetic maps and for a variety of crop improvement programmes will be discussed in this section.
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