**BIOL2269-MOLECULAR AGRICULTURE/ONPS-2083 MOLECULAR PLANT BREEDING**

- Mean

For plant population A

For plant population B

Variance

For plant population A

For plant population B

A.

From the results of the variance in the population above, it is evident that population B is more genetically for height. The height of the difference plants tends to deviate more from the mean than in population A.

B.

If double haploids were used in the experiment it was expected that there could be no variation. This is because the genes in the plants chromosome both the right and left are identical and therefore the reproduced plants would have the characteristic height of the parent plant and hence no variations.

- Solution
- Total number of genes= 35+4+6+35 =80

Total number of recombinant = 4+6=10

Therefore, θ =0.125

Calculating the LOD

Probability that 10 plants out of the 80 are recombinants given that θ=0.125 is

The probability that the two loci are unlikened that θ=0.5; 40 recombinants and 40 non-recombinants plants is

**B.**

When the parental and recombinants are 350, 40,60 and 350

Total number of genes = 800

Total number of recombinants = 100

Calculating the LOD

Probability that 100 plants out of the 800 are recombinants given that θ=0.125 is

The probability that the two loci are unlikened that θ=0.5; 400 recombinants and 400 non-recombinants plants is

The LOD score is higher compared to the initial state hence showing a stronger statistical support.

Scenario: Heterochromatin absent, several marker loci homozygous

The genes are equally spaced on the chromosome and hence there is likeliness of crossover at any point of the chromosome.

Scenario: Heterochromatin present, several marker loci homozygous

The spacing of the genes is influenced by the presence of the heterochromatin; it ensures that the space between the genes in its position they get closely compact.

**A**.

In the first year when the experiment was begun it was expected that there would be less variation in the genes for resistance since crossing is expected and genes for non-resistance and resistance would cross and therefore being less effective. In the second season since this was a double haploid the genes would be more identical and more resistant that is why higher QTL was detected in 2000.

The second season i.e. 2000 was the best year for assessing resistance since it is the year that the disease incidence in plants around the field site were higher. The climatic condition in the area in that year was also favorable for disease spread.

C.

In the first season the QTL outcome presented a scenario where by the plants were considered not to be effectively resistant, however in the coming year the outcome was higher and hence presented a situation whereby it was unpredictable whether there could be a different factor that may have contributed to the outcome.