A wildtype trihybrid soybean plant is crossed to a purebreed

A wild-type trihybrid soybean plant is crossed to a pure-breeding soybean plant with the recessive phenotypes pale leaf l, oval seed (r), and short height (t). The results of the three-point test cross are shown in the table. Traits not listed are wild type.

Calculate the interference value for these data.

Enter your answer to three decimal places (example 0.201)

PART E

Problem 5.23 Phenotype Number Pale 648 Pale, oval 64 10 Pale, short Pale, oval, short 102 6 Oval Oval, short 618 Short 84 98 Wild type 1630 Calculate the recombination fraction between Tand R pair of genes Enter your answer to three decimal places (example 0.201) 0.101 Submit My Answers Give Up Correct Part E Calculate the interference value for these data Enter your answer to three decimal places (example 0.201) Submit My Answers Give Up incorrect; Try Again; 5 attempts remaining

Solution

Answer:

Part D). 0.101 (distance between T & R)

Part E). Interference= 0.231

Explanation:

Shorthand

Number of progeny

l R T

648

I r T

64

l R t

10

l r t

102

L r T

6

L r t

618

L R t

84

L R T

98

Total

1630

Imagine parental combinantion = l RT& L r t

1.      If single cross over (SCO) occurs between l & R

Normal order= l ---------R & L-----r

After cross over= l-----r & L------R

l-----r recombinants are 64+102= 166

L------R recombinants are 84+98= 182

Total recombinants = 348

RF = (348/1630)*100 =21.35%

2.      If single cross over (SCO) occurs between R & T

Normal order= R---------T & r----t

After cross over= R-----t & r------T

R-----t recombinants are 10+84=94

r------T recombinants are 64+6=70

Total recombinants = 164

RF = (164/1630)*100 = 10.06%

3.      If single cross over (SCO) occurs between l & T

Normal order= l -----T & L------t

After cross over= l -----t & L------t

l -----t recombinants are 102+10= 112

L------t recombinants are 98+6=104

Total recombinants = 216

RF = (216/1630)*100 =13.25%

% RF = Map unit distance

The order of genes is -----

l----------13.25 m.u.---------T-----10.06m.u.---R

RF between l & T = 0.133

RF between T & R = 0.101

Expected double cross overs = 0.133 * 0.101 = 0.013

Observed double cross overs = 10% + 6%

= 16/1630= 0.01

Observed double cross progeny are more than the expected double cross over progeny.

Coefficent of coincidence (CC) = Obeserved dco / Expected dco

CC = 0.010/0.013 = 0.769

Interference = 1-CC = 1-0.769 = 0.231

Shorthand	Number of progeny
l R T	648
I r T	64
l R t	10
l r t	102
L r T	6
L r t	618
L R t	84
L R T	98
Total	1630