Question

Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant wiht the reccessive trains colorless aleurone (c1), shrunken kernal (sh), and starchy (wx). The resulting F1 plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting the kernals from about 30 eats of corn yields the following data:

Kernel Phenotype Number
Colored, shrunken, starchy 116
Colored, full, starchy 601
Colored, full, waxy 2538
Colored, shrunken, waxy 4
Colorless, shrunken, starchy 2708
Colorless, full, starchy 2
Colorless, full, waxy 113
Colorless, shrunken, waxy 626
6708
A) Why are these data consistent with genetic linkage among the three genes?
B) Perform a chi-square test to determine if these data show significant deviation from the expected phenotype distribution.
C) What is the order of these genes in corn?
D) calculate the recombination fraction between the gene pairs.
E) what is the interference value for this data set?

Answer 1

D) #recombinant=116+601+4+2+113+625=1462

#nonrecombinant=2538+2708=5246

RF=R/(N+R)=1462/6708=0.2

E) I=1-Q

I-interference

Q-coefficient of coincidence

Q=O2Xo/E2xo(2xo-double crossovers)

O2xo=6

P=(distance from C1 to Sh/100)*(distance from Sh to Wx/100)

=(3.38/100)*(18.28/100)=0.006

E2xo=0.006*6708=40.248

Q=6/40.248=0.15

I=1-0.15=0.85