INTRODUCTION TO PLANT BREEDING

AGRONOMY 815 / CLASS ASSIGNMENTS

P. STEPHEN BAENZIGER, 338 Keim Hall, 472-1538

DEPARTMENT OF AGRONOMY / UNIVERSITY OF NEBRASKA

ASSIGNMENT ONESeptember 4, 1997

Name: ____________________________________________________

1. You have just started a plant breeding program in tomatoes. One of the traits that you are most interested in is yellow fruit color. You cross a yellow tomato by a red tomato and get the following results:

F₁15 red tomato plants

F₂218 red tomato plants:64 yellow tomato plants

Develop a genetic model for this result.

How would you explain your results if in the F₂ you had the following results:

68 red tomato plants: 150 orange tomato plants: 64 yellow tomato plants

2. You discover that the yellow tomato plant is also susceptible to tomato wilt, while the red tomato plant is resistant to tomato wilt. Previous research has shown that tomato wilt resistance is controlled by one dominant gene. What would you expect the phenotype of the F1 plants be for resistance to tomato wilt in the above cross? In the F2, how many plants will be resistant, how many will be susceptible?

How many of the 218 red tomato plants will be resistant, assuming the genes controlling fruit color and resistance to tomato wilt are not linked? Explain your answer.