The term gene interaction describes that several genes influence a particular characteristic. This does not mean, however, that two or more genes or their
products necessarily interact directly with one another to influence particular phenotype. Rather, the cellular function of numerous gene products contributes to the development of commonphenotype. Correspondingly, gene interaction is of two types- intragenic and intergenic. Intragenic interaction. In the intragenic or interallelic interactions, the two alleles of a gene which are present on the same gene locus on the two homologous chromosomes react with each other in such a way as to produce an expression different from the normal dominant-
recessive phenotype, e.g., incomplete dominance, codominance, multiple alleles Incomplete dominance. After Mendel, several cases were recorded where F hybrids were not related to either of the parents but exhibited a mixing of character of two parents.It meansthat two genes of the alelomorphic pair are not related as dominant and receive, butthe dominant gene in heterozygous condition has reduced expression, so that each of them expresses itself partially. This is called :
incomplete dominance. Example: In Mirabilis jalapa (four clock plant) and Antihinum majus (snapdragon or dog flower), there are two types of flower colour in pure state: red and white
