Modifiers may also influence the degree of dominance expressed by another gene. In Abraxas grossulariata, a moth, it could be possible, to establish lines with same gene (lutea - yellow colour) dominant in one case and recessive in the other. This was proved to be due to the effect of modifiers (Ford, 1940).
There are certain other genes, which in addition to their main effect, may also act as modifiers for another but entirely different gene. Such genes having more than one effect are called pleiotropic genes. Some examples of pleiotropic genes are as follows :
It is believed that pleiotropic genes must be more common than earlier suspected, because indirectly every gene may be involved in the expression of more than one traits. Thus most genes, if not all, affect more than one phenotypic traits and are thus pleiotropic in nature.
© 2018 Biocyclopedia | All rights reserved.