An eggplant grower takes a true breeding white eggplant and mates it with a true

Question

An eggplant grower takes a true breeding white eggplant and mates it with a true breeding purple eggplant. This results in a an F1 eggplant plant with fruits--but nobody bother to record the color of the fruit.

The seeds from this fruit are planted after is is allow to self-pollinate, and the the progeny are found to be:

12/16 purple

3/16 white

1/16 orange

Based on this information, what color must the F1 eggplants have been?

Orange

Purple

green

white

A dihybrid plant is selfed, and the offspring shows a phenotypic ratio for flower color of 13 yellow : 3 white. If the same dihybrid plant was testcrossed instead of being selfed, what proportion of the offspring would be expected to be yellow?

Explanation / Answer

In first case the ratio obtained is 12:3:1, which shows that there is existence of dominant epistasis. In dominant episatasis the dominant allele masks the effect of other allele.

Here allele responsible for Purple color is dominating over allele responsible for white color. So the color of F1 progeny will be “Purple”.

If P indicated allele for purple and W for white then Parental type will be: PPww(Purple color) and ppWW ( White color). Their progeny will have genotype: PpWw. As P is masking the effect of W so the F1 progeny will have purple color.

In second case the ratio was found as 13:3, which shows the dominant recessive epistasis. In this case if W is representing the gene responsible for white color then Y is the suppressor of that gene. This s the reason 13 yellow and 3 white colored progenies were found in self cross.

In such case the result of test cross will be: 3:1. So 75% of the progenies will show yellow color.

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