1. Note for instructors: Please see the notes field for answers.
Teaching Genetic Linkage and Recombination through Mapping with Molecular Markers
Lisa McDonnell & Jennifer Klenz
Gels to analyze as part of In-Class Lesson
(see Supplemental Material S1 Lesson Slides, slides 42-45)
Note for instructors: Please see the notes field for answers.

2. MARKER A 50 RESISTANT F2 PLANTS F1 self-fertilized
Note to instructors: we are only listing the molecular marker genotypes for the parent and F1 plants. Students could fill in the resistant and susceptible genotypes (or draw chromosomes labelled with alleles for the parent plants and F1) to help them identify parental and recombinant genotypes.
F1, susceptible
200/400
F1 self-fertilized
Resistant 200/200 X
Susceptible 400/400
MARKER A
50 RESISTANT F2 PLANTS
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
Resistant F2 plants
CONTROLS
# # #24 # # # # # # # #32 # # #35 #36
# #38 #39 # # #42 # #44 #45 #46 # #48 # #50
Linked.
Count the number of recombinant bands/total bands. Recombinant band is the 400 band.
14 high bands/100 bands total *100% = 14% recombinants, 14 map units.
Resistant F2 plants

3. MARKER B 50 RESISTANT F2 PLANTS F1 self-fertilized F1, susceptibleX
Susceptible 100/100
F1, susceptible
350/100
F1 self-fertilized
MARKER B
50 RESISTANT F2 PLANTS
Resistant 350/350
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
CONTROLS
Resistant F2 plants
# # #24 # # # # # # # #32 # # #35 #36
# #38 #39 # # #42 # #44 #45 #46 # #48 # #50
Linked
Count the number of recombinant bands/total bands. Recombinant band is 100.
6 recombinant bands/100 bands total *100% = 6%, or 6 map units.
Resistant F2 plants

4. MARKER C 50 RESISTANT F2 PLANTS F1 self-fertilized F1, susceptible
90/550
F1 self-fertilized
Resistant 90/90 X
Susceptible 550/500
MARKER C
50 RESISTANT F2 PLANTS
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
CONTROLS
Resistant F2 plants
#22 # #24 #25 #26 #27 # #29 # # #32 #33 #34 # #36
# # #39 # #41 # #43 #44 #45 # # # # #50
Independent assortment
550 is the recombinant band
50 recombinant bands/100 total *100% = 50%  independent assortment.
Resistnat F2 plants

5. MARKER D 50 RESISTANT F2 PLANTS F1 self-fertilized F1, susceptible
50/75
F1 self-fertilized
MARKER D
50 RESISTANT F2 PLANTS
Resistant 50/50 X
Susceptible 75/75
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
CONTROLS
Resistant F2 plants
#22 # #24 #25 #26 #27 # #29 # # #32 #33 #34 # #36
# # #39 # #41 # #43 #44 #45 # # # # #50
Likely independent assortment
75 is the recombinant band
49 recombinant bands/100 total *100% = 49%  independent assortment.
Because we already have linkage between the BR locus and two markers on chromosome 1 it is likely that the locus assorts independently from this marker, on chromosome 3. If we screened more plants the percentage recombinants would probably be 50% (or even slightly higher).
Resistant F2 plants

6. MARKER E 50 RESISTANT F2 PLANTS F1 self-fertilized F1, susceptible
675/600
Resistant 675/675 X
Susceptible 600/600
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
CONTROLS
Resistant F2 plants
#22 # #24 #25 #26 #27 # #29 # # #32 #33 #34 # #36
# # #39 # #41 # #43 #44 #45 # # # # #50
Independent assortment
600 is the recombinant band
52 recombinant bands/100 total *100% = 52%  independent assortment.
Resistant F2 plants

7. MARKER F 50 RESISTANT F2 PLANTS F1, susceptible 220/410
F1 self-fertilized
Resistant 220/220 X
Susceptible 410/410
MARKER F
50 RESISTANT F2 PLANTS
Resistant. Susceptible F1
(parent)) (parent)
# # # # # # # # # # # # # # # # # # # # #21
CONTROLS
Resistant F2 plants
#22 # #24 #25 #26 #27 # #29 # # #32 #33 #34 # #36
# # #39 # #41 # #43 #44 #45 # # # # #50
Independent assortment
410 is the recombinant band
51 recombinant bands/100 total *100% = 51%  independent assortment.
Resistant F2 plants