1. Gene interaction - Introduction
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Basics for undergraduate/university students The phenomenon of two or more genes affecting the expression of each other in various ways in the development of a single character of an organism is known as GENE INTERACTION.
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1. Gene interaction - Introduction
- 1. P a g e | 1 GENE INTERACTION UNIT II (B): GENE INTERACTIONS Mendel and other workers assumed that characters are governed by single genes but later it was discovered that many characters are governed by two or more genes. Such genes affect the development of concerned characters in various ways; this lead to the modification of the typical Dihybrid ratio (9:3:3:1) or trihybrid (27:9:9:9:3:3:3:1). Numerous deviations have been recorded in which different kinds of interactions are possible between the genes. The phenomenon of two or more genes affecting the expression of each other in various ways in the development of a single character of an organism is known as GENE INTERACTION. Most of the characters of living organisms are controlled/ influenced/ governed by a collaboration of several different genes. BATESON suggested concept of gene interaction and this concept is called Bateson’s factor hypothesis. KINDS OF GENE INTERACTIONS 1. INTRA- ALLELIC GENE INTERACTIONS The genetic interactions between the alleles of a single gene are referred to intra- allelic gene interactions. Commonly referred as Intragenic interaction 2. INTER-ALLELIC GENE INTERACTIONS The genetic interactions between the alleles of one gene with the allele of other gene are referred to inter- allelic gene interactions. Commonly referred as Intergenic interaction Some of the interallelic gene interactions to be discussed are tabulated below. Interallelic gene interaction Example Parental generation F1 generation F2 Ratio A Complementary gene interaction Flower color in Lathyrus odoratus White X White ccPP X CCpp Purple CcPp 9:7 B Supplementary gene interaction Grain color in Maize Purple X White RRPP X rrpp Purple RrPp 9:3:4 C Epistasis i Dominant Epistasis Fruit color in Cucurbita pepo White X Yellow WWyy X wwYY White WwYy 12:3:1 ii Recessive Epistasis Coat color in Mice Black X Albino CCaa X ccAA Agouti CcAa 9:3:4 D Non- Epistasis Comb pattern in Poultry Rose X Pea RRpp X rrPP Walnut RrPp 9:3:3:1