Experience Using GEM Germplasm in a Public Breeding Program

1
Experience Using GEM Germplasm in a Public
Breeding Program

• Jim Hawk, Tecle Weldekidan, and Travis Frey
• Department of Plant and Soil Sciences

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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

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Topics for Discussion

1. Choice of parental germplasm
2. Breeding methods/strategies 
3. Hybrid evaluation
4. Opportunities/challenges
5. Summary

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Choice of Parental Germplasm
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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 pre-breeding?
• Other accessions ?

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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

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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

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Recommended GEM Breeding Populations Evaluated at
Three Locations, 2003
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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

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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

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Number of S1 Ears Selected from GEM Breeding
Crosses
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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

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Number of SS S2 Lines Selected from GEM S1
Families
14
Number of Non-SS S2 Lines Selected from GEM S1
Families
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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, USDA-GEM Ames-1 rep
• Second year YT- 2 testers x 8 locations

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DK212TN11a10 Lines Crossed to Pioneer SS Tester
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CUBA164 Lines Crossed to LH185
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Opportunities/Challenges

• Trait improvement using selected GEM lines -
  Grain quality, disease, insect resistance, etc.
• Use additional testers
•        

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Opportunities/Challenges

• Sister line mapping studies
• DKXL212N11a-365-1-1-2-1-1(DE4)
• DKXL212N11a-365-1-1-1-1
• Recycling
• - Further improvements needed for
  commercialization

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DE4 Recycled Lines Crossed to LH244
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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

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Summary

• Germplasm for new breeding crosses - Lines,
  improved populations etc.
• Useful genetic variation within adapted GEM
  families

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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

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Acknowledgements

• Wilfredo Salhuana
• USDA-GEM, Ames
• Holdens Foundation Seeds
• Mycogen Seeds
• Pioneer Hi-Bred Int.