(1995). After the preamplification reaction, the reaction mixture was diluted to 150 μl with double distilled
H2O (dd H2O). The 10 μl PCR selective amplification system contained 1 μl of product from the diluted preamplification
reaction, 25 ng of both selective primers, 0.3 units of Taq DNA polymerase, 0.2 mM of each dNTP, 1.5 mM MgCl2 1X PCR buffer. All amplification reactions were performed in a Touch gene model thermocycler (Techne). Initially, three individuals from three studied strainswere chosen to test the variation of 66 primer combinations (data not shown). With these individuals thepolymorphism rates and the total number of bands with the 66 primer combinations were evaluated. The most useful primer combinations were considered those having the highest polymorphism rate that also
generate a reasonable number of clearly detectable
total fragments. Using results from the evaluation of