Mr. Wiseman has a small backyard where he has grown cherry tomatoes for many yea

Question

Mr. Wiseman has a small backyard where he has grown cherry tomatoes for many years but that hard cannot grow more than 40 plants. His favorite variety is a pure line that produces various colors of the fruit peel and contains normal levels of lycopene in the fruit. He happened to know there was a new unreleased line with 90% higher vitamin C content than his current variety, but that was a purple variety. Mr. Wiseman was told that if he could cross this line with his favorite variety, he would get a new variety that has multi color and high vitamin C containing cherry tomatoes. However, from this cross he got frustrated because he got 21 and 19 plants showing normal vitamin C and high vitamin C contents respectively, but all the fruits showed purple color! He did not have any information about the unreleased line he got. Can you explain to him and help him select the pure line of multi colored and high vitamin C containing tomatoes as soon as possible? Your strategy should also be realistic given the limitation of his small backyard. For your convenience, you can assume peel color and vitamin C levels are controlled by 2 independent genes. Mr. Wiseman has a small backyard where he has grown cherry tomatoes for many years but that hard cannot grow more than 40 plants. His favorite variety is a pure line that produces various colors of the fruit peel and contains normal levels of lycopene in the fruit. He happened to know there was a new unreleased line with 90% higher vitamin C content than his current variety, but that was a purple variety. Mr. Wiseman was told that if he could cross this line with his favorite variety, he would get a new variety that has multi color and high vitamin C containing cherry tomatoes. However, from this cross he got frustrated because he got 21 and 19 plants showing normal vitamin C and high vitamin C contents respectively, but all the fruits showed purple color! He did not have any information about the unreleased line he got. Can you explain to him and help him select the pure line of multi colored and high vitamin C containing tomatoes as soon as possible? Your strategy should also be realistic given the limitation of his small backyard. For your convenience, you can assume peel color and vitamin C levels are controlled by 2 independent genes.

Explanation / Answer

The peel color of tomato is determined by the presence of P gene which determined the presence of purple color and p gene which determined the presence of multicolor. Vitamin C levels are determined by the presence of C gene.

The genotype of pure line which produces tomatoes with multicolor peel and normal levels of vitamin C are (pp, cc). Newline of tomatoes had purple color and high levels of vitamin C.

F1 offsprings are all purple. So, the genotype of the newline for purple color should be PP and it following autosomal dominant pattern of inheritance. Regarding vitamin C levels, half of F1 have normal levels and half have higher levels. So, the genes for vitamin C must be in heterozygous state Cc in the newline of tomato.

Pureline variety - (pp, cc)

New variety - (PP, Cc)

We need pureline variety with multicolor peel and high vitamin C whose phenotype is (pp, CC). This can be produced by selecting a new variety with genotypes Pp, Cc. This genotype can be identified by crossing new variety with old variety and among the F1 offsprings, half purple and half multicolor; half with normal vitamin C and half with high vitamin C are observed.

Select two such plants with genotypes (Pp, Cc). The cross between these two plants are represented below.

This cross produces three offsprings with multicolor peel and high levels of vitamin C. Among these three, one is pureline (ppCC). Thus pureline tomato variety with multicolor peel and high vitamin C are produced.

pc pc pc pc PC PpCc PpCc PpCc PpCc PC PpCc PpCc PpCc PpCc Pc Ppcc Ppcc Ppcc Ppcc Pc Ppcc Ppcc Ppcc Ppcc

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.