Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 109

In disease resistance breeding, plant breeders cross an elite susceptible cultivar with one that has disease resistance. Consider a cross between two populations, susceptible × resistant. If the gene frequencies of an allele A in the two populations are represented by P ₁ and P ₂ , the gene frequency in the F ₁ = (P ₁ + P ₂ )/2 = p. Assuming the frequency of the resistance gene in the resistant cultivar is P ₁ = 0.7 and that in the susceptible elite cultivar is P ₂ = 0.05, the gene frequency in the progeny of the cross p would be obtained as follows;

Consequently, the gene frequency for the resistant trait is reduced by about 50% (from 0.7 to 0.375).