Experience Using GEM Germplasm in
a Public Breeding Program
Jim Hawk, Tecle Weldekidan, and Travis Frey
Department of Plant and Soil Sciences
GEM Objectives
• To improve and broaden the
germplasm base
• Traits targeted are agronomic
productivity, disease and insect
resistance, and value-added
• The ultimate target is to release
lines for applied and basic
research
Topics for Discussion
1. Choice of parental germplasm
2. Breeding methods/strategies
3. Hybrid evaluation
4. Opportunities/challenges
5. Summary
Choice of Parental Germplasm
Temperate
Tropical
Tropical hybrids
Total
LAMP
GEM
Races or
Accessions Mixtures
78
27
100
47
Accessions Races or
or Hybrids Mixtures
23
8
28
12
7
58
20
178
74
Choice of Parental Germplasm
• Breeding crosses- accession x elite
inbred line
• Elite inbred lines- all lines not more
than one breeding cycle removed
from a commercial product
• Over 550 breeding crosses – which
ones should receive priority for prebreeding?
• Other accessions ?
Breeding Cross Evaluations
Locations:
USDA – GEM, Ames – Mike Blanco
Golden Harvest, IL – Kevin Montgomery
University of Delaware, Newark, DE
No. of Breeding Crosses Evaluated:
2003 – 168
2004 – 173
Traits Evaluated in Breeding Crosses
•
•
•
•
•
•
•
•
Adaptability
Days to flowering
Ear and plant height
Ear traits
Disease and insect resistance
Root and stalk lodging
Stay green
Plant appearance
Recommended GEM Breeding Populations
Evaluated at Three Locations, 2003
Pedigree
ANTIGO03:N1218
AR16026:S1716
AR16035:S0209
BR52051:N04
BR52051:S1711b
CL-G1707:S18
FS8A(T):N1804
GUAT209:S1308d
PASC014:N0424
UR05071:S0409
Clinton, IL
X
X
X
Ames, IA
X
X
X
X
X
X
X
X
X
X
X
X
Newark, DE
X
X
X
X
X
X
X
Breeding Crosses Utilized at
the University of Delaware
• ~10/year
• Most 75% corn belt, some 50%
• Grow ~1200 plants/population
• Self 400-600 plants/population
Breeding Methodology
• Pedigree
• Mass selection for more heritable traits
- plant and ear height
- maturity
- ear traits
- disease and insect resistance
- root and stalk strength
• Balance offensive and defensive traits
Number of S1 Ears Selected from GEM
Breeding Crosses
Pedigree
AR16035:S0209
BR52051:S1711b
DKXL212:S0943b
BR52051:N0417
No. of rows No. of S1 Comments
grown ears saved
40
80
Early, short, good stalks &
roots, good grain qual.
Good seedling vigor
40
67
Heavy ASR, good SG
40
141
Excellent stalks, roots, &
grain texture
40
96
More ASR, good roots,
smut, good seedling vigor
Breeding Methodology
• Select 0-160 S1 ears/breeding cross
• S1 families
 6-8/family
Family and mass selection for more
heritable traits
Sampling within best S1 families – 1-3
S2 ears
Goal – 50 S2 ears minimum from better
populations
• Discard poor breeding crosses
Number of SS S2 Lines Selected from
GEM S1 Families
Pedigree
AR01150:S0121
AR16035:S3115
DKXL212:S0912
UR11003:S1823
S1
S2
No. S1
Lines Lines
Families
Grown Selected Represented %
54
43
264
52
46
14
271
0
30
8
153
0
55.6
18.6
58.0
0
Comment
Nice ears, healthy, short
Albinos
Good family, some ECB
Poor plant health
Number of Non-SS S2 Lines Selected
from GEM S1 Families
Pedigree
AR03056:N1625
BR51721:N2012
DKL212T:N11a10
DKB830:N11b20
Comment
S1
S2
No. S1
Lines Lines
Families
Grown Selected Represented %
66
47 34
51.5 Healthy family
28
35 20
71.4 Healthy family
49
69 37
75.5 Good family
25
9 6
24.0 Late
Hybrid Evaluation
• ~50 S2 testcrosses + 3 commercial
checks
• Use testers with good GCA and
agronomics (roots, stalks, disease and
insect resistance)
• Locations/reps: 3 DE (1 dryland, 2
irrigated) with 2 reps/location, USDAGEM Ames-1 rep
• Second year YT- 2 testers x 8 locations
DK212T:N11a10 Lines Crossed to Pioneer SS Tester
Hybrid
Yield
Bu/A
%
Moisture
Y/M
%
Lodging
Pioneer 31G98
223.4
22.5
10.3
2.9
DK212T:N11a10)-107-2
215.9
22.7
9.7
3.7
DK212T:N11a10)-156-1
212.2
22.6
9.7
2.7
Pioneer 33B51
211.1
21.9
9.8
2.8
DK212T:N11a10)-135-2
193.6
20.9
9.5
5.7
CUBA164 Lines Crossed to LH185
Hybrid
Yield
Bu/A
%
Moisture
Y/M
%
Lodging
Pioneer 31G98
212.8
23.0
9.5
6.6
Pioneer 33B51
198.3
21.2
9.5
9.0
CUBA164:S1511b)-1-1-1
197.8
21.5
9.3
5.0
CUBA164:S2012)-24-2
193.8
21.3
9.3
5.7
Opportunities/Challenges
• Trait improvement using selected
GEM lines - Grain quality, disease,
insect resistance, etc.
• Use additional testers
Opportunities/Challenges
• Sister line mapping studies –
DKXL212:N11a-365-1-1-2-1-1(DE4)
DKXL212:N11a-365-1-1-1-1
• Recycling
- Further improvements needed for
commercialization
DE4 Recycled Lines Crossed to LH244
Pedigree
Yield
Bu/A
%
Moisture
Y/M
%
Lodging
Pioneer 31G98
209.3
23.6
9.1
3.1
DE4.DE1/DE4)-13
181.1
23.6
7.7
3.3
DE4.DE1/DE4)-43
180.2
22.5
8.1
3.8
DE4.DE1/DE4)-6
178.8
20.9
8.6
7.4
Pioneer 33B51
174.0
22.0
8.0
2.0
LH244.DE4
156.3
22.6
6.9
7.2
Summary
• Focus on adaptability, agronomics,
disease/insect resistance first
- Breeding cross evaluations
- Family and mass selection for
more heritable traits
• May be useful to re-evaluate better
breeding crosses in additional years
Summary
• Germplasm for new breeding
crosses - Lines, improved
populations etc.
• Useful genetic variation
within adapted GEM families
Summary
•
•
•
•
Practice art of plant breeding
Better to discard earlier than later
Focus on better germplasm
Plant breeders:
Short-term pessimists
and
Long-term optimists
Acknowledgements
•
•
•
•
•
Wilfredo Salhuana
USDA-GEM, Ames
Holden’s Foundation Seeds
Mycogen Seeds
Pioneer Hi-Bred Int.