Thus if the two loci are in the dominant state AL leaves rea

Thus, if the two loci are in the dominant state (A-L-), leaves readily produce hydrogen cyanide when crushed. If only the A locus is producing a functional product, cyanogenesis still occurs, but at a slow, spontaneous rate. The plant is acyanogenic if the first gene product is absent. From a cross involving plants heterozygous at both loci, what is the probability that any one of the resulting clover plants will be:
1. Cyanogenic
2. Acyanogenic
3. Show slow cyanogenesis
A Locus L locus Precursor …> Precursor………___ glucoside ………… hydrogen cyanide

Solution

This case is an example of complementary gene epistatis. Let us start with creating heterozygotes for both of the characters.

AaLl and AaLl

When they are crossed, the following progenies are produced

Cyanogenic = AALL

Slow cyanogenic = AAlL, AALl, AAll

Acyanogenic = aALL, aAlL, aALl, aAll, AaLL, AalL, aaLL, aalL, aaLl, Aall, aaLi, aall

So, the phenotypic ratio = 1:3:12

Probability of Cyanogenic = 1/16 = 0.0625

Probability of Slow cyanogenic = 3/16 = 0.1875

Probability of Acyanogenic = 12/16 = 0.7500

AL Al aL al
AL AALL AAlL aALL aAlL
Al AALl AAll aALl aAll
aL AaLL AalL aaLL aalL
al aaLl Aall aaLl aall
Thus, if the two loci are in the dominant state (A-L-), leaves readily produce hydrogen cyanide when crushed. If only the A locus is producing a functional prod

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