Gene interaction Epistasis prepared by Dr' Paul Kusolwa

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Gene interaction Epistasisprepared by Dr. Paul
Kusolwa

• Complementary interaction 97
• Dominant epistasis 12 3 1 A gtB
• Duplicate dominant epistasis 151 A and B gives
  new phenotype
• Dominant Suppression 133 A suppress B locus at
  dominant state

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• Fruit colors in sweet pepper

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F2
1 Green
9 Red
3 Yellow
3 Brown
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Dominant epistasis Solid fruit color in summer
squash

• Modified Dihybrid ratio for fruit color
• 1231 ratio
• Alleles W and w for color expression
• W white fruits (weak coloration), w recessive
  for colored fruits
• At another locus Y for yellow fruits
• Y is dominant to y Yellow fruits
• y recessive green fruits
• Both w and y when present in recessive conditions
  both gives green fruit color
• Zucchini summer squash
• selection against the dominant W alleles

Dominant Epistasis - W negates the dominance of Y
for color expression
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Fruit shapes in squash
Di locus Dominant to spherical or
pyriform Duplicate genes with cumulative
effects When Di is present together with
Spherical S locus Di is dominant Disc
fruits When Di present with recessive s
spherical fruits When didi/ss long or pyriform
fruits Modified Ratio 9 6 1
9 Discs Di_S_
1 Pyriform di/s
6 Spherical Di/s di/S_
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Complementary interaction
Pathway involving two genes Wt warty fruits
Dominant to non warty wt Hr hard rind hr
intermediate texture 97
B_ Hr_ Wt_ Y_
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Bicolor fruits locus B pleiotropic for fruits
and leaves For yellow and green color patches BB
or Bb Extent of yellow or green dosage of
another incompletely dominant, additive to
modifier genes. Ep1 and Ep 2 Ep1 and Ep2 alleles
are involved in enlarging the yellow
patches Genotypes Bb with a dosage of 0 to 1 Ep
alleles bicolor green and yellow fruits Dosage
of 2-4 dominant alleles Ep extends the yellow
coloration Genotypes 9 B_Ep_ Extended yellow
3 B_epep Yellow narrow 3 bbEp_ Green
extended 1bbepep green
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Three or more genes interactions in ornamental
gourds Gb green bands gb for no bands Gr/G
green rind (gr/g buff skin) L-2 color
intensity (yellow /orange)
Gr Gb L-2 Ep-1/2
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B_ bicolor L-2 intensity Pro ovary
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momo-1
Complementary recessive for loss of green fruit
color before maturity mo-1 Mature orange
color mo-2 Mature orange
MoMo -1