Two strains of a plant, designated P1 and P2, produce flowers of the same color, which is purple. Each of these strain is crossed with a pure-breeding strain A, which produce pink flowers. The F₁ progeny plants of each cross have pink flowers. Self-fertilization of the F1 progeny of each cross resulted in 1/4 plants with purple flowers and 3/4 plants with pink flowers. In how many genes do variable alleles segregate in the two crosses?