Gene interaction

Gene interaction
by hafiz m waseem

1. UNIVERSITY OF EDUCATION LMC ASSIGNMENT TOPIC:_GENE INTERACTION UNIVERSITY OF EDUCATION LMC

2. HAFIZ M WASEEM UNIVERSITY OF EDUCATION LAHORE

3. CONTENTS Gene interaction Epistasis Dominant epistasis Recessive epistasis Duplicate dominance epistasis Dominant and recessive or inhibitory recessive Double recessive References CONTENTS

4. Mendal concepts

5. GENE INTERACTION "When expression of one gene depends on the presence or absence of another gene in an individual, it is known as gene interaction.” GENE INTERACTION

6. TYPES OF GENE INTERACTION Gene interactions can be classified as a) Allelic/ non epistatic gene interaction: _ This type of interaction gives the classical ratio of 3:1 or 9:3:3:1 Genetic interactions between the alleles of a single gene are referred to as allelic or intra- allelic interactions. b) Non-allelic/ epistatic gene interaction:_ In this type of gene interaction genes located on same or different chromosome interact with each other for their expression. Non-allelic or inter-allelic interactions also occur where the development of single character is due to two or more genes affecting the expression of each other in various ways.

7. EPISTASIS:_ In epistasis, one gene masks or interferes with the expression of another. ... An example of epistasis is pigmentation in mice. The wild-type coat color, agouti (AA), is dominant to solid-colored fur (aa). In mice, the agouti coat color (A) is dominant to black or gray. A gene at a separate locus (C) is responsible for pigment production. The recessive c allele does not produce pigment, and a mouse with the homozygous recessive cc genotype is albino regardless of the allele present at the A locus. Thus, the C gene is epistatic to the A gene. HYPOSTASIS The alleles at the epistatic gene mask the effects of alleles at another gene. The gene whose alleles are masked or repressed is called the hypostatic gene action. EPISTASIS

8. Epistatic Hypostatic Epitatic Hypostatic

9. CLASSIFICATION OF EPISTATISIS The following are types of epistasis gene interaction. The types are: Dominant Epistasis Recessive Epistasis Dominant [Inhibitory] Epistasis Duplicate Recessive Epistasis Duplicate Dominant Epistasis

10. Dominant Epistasis [12 : 3 : 1 Ratio]: When a dominant allele at one locus can mask the expression of both alleles (dominant and recessive) at another locus, it is known as dominant epistasis. In other words , the expression of one dominant or recessive allele is masked by another dominant gene. . An example of dominant epistasis is found for fruit colour in summer squash. There are three types of fruit colours in this cucumber, viz., white, yellow and green. White colour is controlled by dominant gene W and yellow colour by dominant gene G. White is dominant over both yellow and green. The green fruits are produced in recessive condition (wwgg). A cross between plants having white and yellow fruits produced F1 with white fruits. Inter-mating of F1 plants produced plants with white, yellow and green coloured fruits in F2 in 12 : 3 : 1 ratio .

11. G1dominant allele supress G2 dominant allele No role of recessive gene White fruit. Yellow fruit. Green fruit WWgg. GGww. wwgg W________ white fruit ww_______yellow wwgg_______green

12. Recessive Epistasis [9:3:4 Ratio]: When recessive alleles at one locus mask the expression of both (dominant and recessive) alleles at another locus, it is known as recessive epistasis. This type of gene interaction is also known as supplementary epistasis.

13. Epistasis type 3:_ Duplicate Dominant Epistasis [15 : 1 Ratio]: Both dominant show their expression A............heart shape B..............heart shape aabb...........narrow shape

14. Dominant [Inhibitory] Epistasis [13 : 3 Ratio]: In this type of epistasis, a dominant allele at one locus can mask the expression of both (dominant and recessive) alleles at second locus. This is also known as inhibitory gene interaction. An example of this type of gene interaction is found for anthocyanin pigmentation in rice. The green colour of plants is governed by the gene I which is dominant over purple colour. The purple colour is controlled by a dominant gene P. When a cross was made between green (IIpp) and purple (iiPP) colour plants, the F1 was green. Inter-mating of F1 plants produced green and purple plants in 13 : 3 ratio in F2 .

15. Duplicate Recessive Epistasis [9 : 7 Ratio]: When recessive alleles at either of the two loci can mask the expression of dominant alleles at the two loci, it is called duplicate recessive epistasis. This is also known as complementary epistasis. The best example of duplicate recessive epistasis if found for flower colour in sweet pea. The purple colour of flower in sweet pea is governed by two dominant genes say A and B. When these genes are in separate individuals (AAbb or aaBB) or recessive (aabb) they produce white flower. A cross between purple flower (AABB) and white flower (aabb) strains produced purple colour in F1. Inter-mating of F1 plants produced purple and white flower plants in 9 : 7 ratio in F2 generation

16. References Gilbert-Diamond, D., & Moore, J. H. (2011). Analysis of gene-gene interactions. J.H. Moore, in Brenner's Encyclopedia of Genetics (Second Edition), 2013 Mani R,St Onge RP,Hartman JLt,Giaever G,Roth FP (2008) Defining genetic interaction. Proc Natl Acad Sci U S A 105: 3461.6 .Roth FP,Lipshitz H,Andrews BJ (2009) Q&A: epistasis. J Biol 8: 35. .Costanzo M,Baryshnikova A,Bellay J,Kim Y,Spear ED (2010) The genetic landscape of a cell. Science 327: 425.31 Hillenmeyer ME,Fung E,Wildenhain J,Pierce SE,Hoon S (2008) The chemical genomic portrait of yeast: uncovering a phenotype for all genes. Science 320: 362.5