INTRODUCTION TO PLANT BREEDING

AGRONOMY 815 / CLASS ASSIGNMENTS


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

DEPARTMENT OF AGRONOMY / UNIVERSITY OF NEBRASKA



PROBLEM SET 6Due November 4, 1997


Name: ________________________________________________________________________




1.You make a cross between the following two homozygous individuals:

Purple seeded, mildew susceptible x White seeded, mildew resistant

F1 Purple seeded, mildew resistant

F2 : 675 Purple seeded, mildew resistant, 225 Purple seeded, mildew susceptible,
525 White seeded, mildew resistant, 175 White seeded, mildew susceptible




This is not a traditional 9:3:3:1 ratio, but you also know that these traits are not linked. Considering each trait independently can you develop/remember a genetic model for the inheritance of purple seeded vs. white seeded; the inheritance of mildew resistance vs. mildew susceptibility?










Using your genetic model, you develop 640 single seed descent lines in the F6 generation. You harvest all the plants that have purple seed and mildew resistance. Of those plants you harvested, how many will be true breeding and how many will segregate for seed color or for mildew resistance?










2. Is it possible to develop a double cross hybrid ((AxB) x (CxD)) using only cytoplasmic male sterility? Explain your answer.