Presentation on theme: "Development and Characterization of Maize-Teosinte Introgression Libraries Sherry Flint-Garcia USDA-ARS Columbia, MO."— Presentation transcript:
Development and Characterization of Maize-Teosinte Introgression Libraries Sherry Flint-Garcia USDA-ARS Columbia, MO
Outline Introduction Development of Teo NIL Libraries Applications of Teo NIL Libraries Lofty Ideas
Evolutionary Genetics of Maize Domesticated from Zea mays ssp. parviglumis, existed/exists in an intermediate form of landraces Single domestication event in Mexican highlands 6,000~9,000 years ago Selection
Development of Teo NIL Libraries B73 × teosinte (parviglumis) 10 accessions F1 : B73 × teosinte teosinteBC1BC2BC3BC4B73F1
Library Development 161 BC4S2 NILs: 2 libraries (done in 2009) 643 BC4S2 NILs: 8 libraries (done in 2008) 83 BC4DH NILs: duplicated library 887 Near Isogenic Lines (NILs) Z031E0035 Z035E0012 Illumina GoldenGate 768 SNP assay
Introgression Stats # Avg. # Avg. % Avg. % Avg. % PopulationLines RegionsTeosinteHet. TeozygousCoverage Ames Ames Ames Ames Ames Ames Ames PI PI PI PI DH Expected Genotype Ratios for BC4S2 (sibbed): 95% BB, 3% BT het., 1.5% TT
Library Coverage c1c2c3c4c5c6c7c8c9c10 10 maize-teosinte libraries 804 BC4S2 NILs and 83 BC4DH NILs Each line: 2.3 chromosomal segments 4.1% of the teosinte genome 3.3X genome coverage
BC4S2 vs BC4DH Coverage c1c2c3c4c5c6c7c8c9c10
Applications of Teosinte NILs
1. Empirical Genetics Questions 1000 Selected Genes What do these selected genes do? What traits were targeted by artificial selection during domestication/breeding? Are selected genes important? Auxin response factor, ARF (bp) Diversity (π) Inbreds Teosinte Tillering/branching? ? Auxin-mediated Protein Degradation Could be any trait!
2. Evaluate Allele Series Examine the range of allele effects of maize versus teosinte. Validate QTL identified by NAM. Trait Value B73 Maize Alleles Teosinte Alleles
A Brief Digression Nested Association Mapping (NAM) Flowering Time Ed Buckler, Jim Holland, Mike McMullen, et al Buckler, et al. (2009) Science
Flowering Genetic Architecture At least 39 QTL explain flowering architecture Genetic architecture of maize is very complex and very different than Arabidopsis. Buckler, et al. (2009) Science
Many QTL with small Effects 333 alleles significant at P = Only 7 alleles had more than 24 hour effect. Buckler, et al. (2009) Science 12h Significant QTL 24h36h Increase Flowering Time Decrease Flowering Time Additive Allelic Effects
Allele Series 69% of QTLs had both alleles with both positive and negative effects. Buckler, et al. (2009) Science 1 39 ……………….………………. QTL……………………….………. Additive Allelic Effects (days)
“Gene Stacking” Large differences in parental lines (32 day span) are the product of stacking large numbers of modest effect QTL. Buckler, et al. (2009) Science EarliestLatest
Back To Teosinte
Flowering Evaluation ~850 NILs from 10 libraries Days to Anthesis (DTA) from: Ithaca, NY (2 reps), Rebecca Nelson & Oliver Ott Ithaca, NY (2 reps), Buckler lab Raleigh, NC (8 reps), Peter Balint-Kurti Madison, WI (1 rep), Loren Trimble St. Paul, MN (1 rep), Nathan Springer Columbia, MO (4 reps) TOTAL 18 reps
Teosinte Introgressions vs. NAM Additive Effect (days) Teosinte NILs 1.1 NAM Photo- period Gene?
Sucrose UDP Glucose ADP Glucose AmyloseAmylopectin sh1 : sucrose synthase sh2, bt2 : ADP-glucose pyrophosphorylase su1 : debranching enzyme ae1 : SBE-IIB wx1 : g.b starch synthase Selected Genes in Maize Starch Pathway; Whitt et al Reintroduce Genetic Variation Biological hypothesis: A loss of genetic variation results in a loss of phenotypic variation. Breeding hypothesis: We can improve modern traits.
Kernel Traits CarbohydrateProteinFat Percent of Kernel Weight Teosinte (N = 11) Landraces (N = 17) Inbred Lines (N = 27) Flint-Garcia et al. (2009) TAG seed size β γ α family δ Zein Profile
Teosinte NIL Evaluations Hibbard – Corn Rootworm Resistance Buckler – Flowering Brutnell – Shade Avoidance Response Balint-Kurti – SCLB and GLS Smith – Smut Tracy – Germination AgReliant – Agronomic Traits Nelson – NCLB Hoekenga – Iron Bioavailability Harmon – Circadian Clock Dallo – Mal de Rio Cuarto Disease Flint-Garcia – Starch, Protein, Oil Zein Profile Amino Acid Profile
Lofty Ideas 2010 Agronomics Fertilizer Density Mechanization ? Select only on yield ideotype 7000 BC