[Spontaneous mutation variation (quantitative manifestation) of some traits of the garden rose]

Quantitative variability of four traits (anthocyan coloration, flower aroma, double-flowering capacity, and a flower size) in spontaneous gemmacous mutants (sports) of garden rose may be not accidental but preferably orientated to the increase or decrease in the trait manifestation in the case of transaggressive inheritance by initial hybrid forms of the increased or decreased level of these traits in parents. Revealing this regularity enabled us to evolve a hypothesis explaining the decrease or increase in trait quantitative manifestation in sports by inactivation or elimination resulting from mutations in dominant alleles of the polymer genes responsible either for increasing or decreasing in phenotypic expression. Thus, if the parents of an initial form are known, it is possible to forecast in what way the quantitative characters in somatic mutants of the initial form will change, accidentally or getting preferably higher or lower.