The Australian grass tree, from the genus Xanthorrhoea in the lily family, grows to a height of about 4.5 m, bears long narrow leaves in a tuft at the top of the trunk, and produces yellow or white flowers in a spike above the leaves. A yellow-flowered tree was self-crossed. The seeds were collected and planted. The resulting progeny were 28 yellow-flowered trees and 8 white-flowered trees.

Write the genotypes of the parental yellow-flowering tree and its progeny, using Y and y to designate the different flower-colour alleles

Parental genotype: ?

Genotype(s) of yellow-flowering progeny (if more than one genotype, separate genotypes with a comma and a space, eg. AA, Aa):?

Genotype(s) of white-flowering progeny (if more than one genotype, separate genotypes with a comma and a space, eg AA, Aa): ?

To determine the genotypes of the parental yellow-flowering tree and its progeny, we need to use some genetic principles. In this scenario, the yellow-flowered tree was self-crossed, which means it is likely to be homozygous for the flower color gene.

Let's assign the yellow flower color allele as "Y" and the white flower color allele as "y". Since the tree was self-crossed, both of its alleles must be the same.

Therefore, the genotype of the parental yellow-flowering tree would be YY, indicating that it is homozygous for the yellow-flower color allele.

Now, let's analyze the progeny. Out of the resulting progeny of 36 trees, 28 are yellow-flowered trees and 8 are white-flowered trees. This gives us a phenotypic ratio of 28:8, which simplifies to 7:2.

To determine the possible genotypes of the yellow-flowering progeny, we can deduce the potential combinations of alleles that would result in a yellow flower color. Since the parental tree is homozygous for the yellow allele (YY), all progeny will have at least one yellow allele. Therefore, the possible genotypes for the yellow-flowering progeny are YY (homozygous) and Yy (heterozygous).

For the white-flowering progeny, the only way to have a white flower color is if they inherit two copies of the white allele (yy). Therefore, the genotype of the white-flowering progeny would be yy (homozygous for the white allele).

To summarize:

Parental genotype: YY
Genotype(s) of yellow-flowering progeny: YY, Yy
Genotype(s) of white-flowering progeny: yy