over-suppression unilateral over-suppression 2013-06-05T21:54:08Z An effect in which the perturbation of one gene (which has no individual effect on the phenotype in question), when combined with a perturbation of another gene (which causes the phenotype in question), results in a mutant phenotype opposite (relative to wild type) to that of the original phenotype. With respect to any single quantifiable phenotype, this may be expressed as an inequality as: E = a < b = wt < ab OR ab < wt = b < a = E where 'a' and 'b' are the observed phenotype values of the individual perturbations, 'ab' is the observed phenotype value of the double perturbation, 'E' is the expected phenotype value of the double perturbation, and 'wt' is the wild type phenotype value. MI:1295 PSI-MI orchard