Type of epistasis where the recessive alleles “aa” are epistatic over (supress) alleles B/b. In other words: if one gene is homozygous recessive (aa), then the effect of another gene (B/b) does not come to expression. Hence, a backcross of A.B. x aabb segregates in the offspring as A.B. / aa.. / A.bb in a ratio of 9:4:3. This type of inheritance may occor for the flower colour trait, for example.
Synonym: cryptomery
BT: epistasis