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Genomic Analyis of Seed Quality Traits in Corn

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ZDS = Zeta Carotene Desaturase. Y1 = Phytoene Synthase ... Variation in Phytoene Desaturase and Zeta Carotene Desaturase Readily Revealed ... – PowerPoint PPT presentation

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Title: Genomic Analyis of Seed Quality Traits in Corn


1
Which One is Highest for ProVitamin A
Concentration?
2
  • Survey Carotenoid Variability in
  • Genetically Diverse Maize Inbreds
  • - Beta-Carotene, Alpha-Carotene
  • Beta-Cryptoxanthin Pro-Vitamin A
  • - Lutein, Zeaxanthin - Antioxidants
  • Genetic QTL Studies
  • Facilitate Breeding for Levels of
  • Pro-Vitamin A for Human Nutrition
  • Creation Public Synthetics to Share

3
Carotenoid Biosynthetic Pathway
GGPP
Lycopene
PSY
y1
Phytoene
b- LCY
b- LCY e- LCY
PDS
2x
Phytofluene
vp5


a- carotene
z- carotene
b- carotene
ZDS
2x
Neurosporene
b-crytptoxanthin

vp9
Zeaxanthin
Lutein
4
Need Quantify- Get Specific Carotenoid
Concentrations Expensive Need to Reduce Costs
HPLC Chromatogram 450 nm
Zeaxanthin
AU
Lutein
AU
ß-cryptoxanthin
a-carotene
ß-carotene
Note More Lutein and Zeaxanthin - Do Not
Have ProVitamin A
5
Means and Ranges from 2002 Survey Diverse Genetic
Set of Inbreds Goodman Buckler
-Mean Two Replicates 85 of 102 Inbreds Able to
Produce Seed -Heritabilities are Very High .7 -
.9
6
2003 Survey Expanded Set of 300 Lines to Sample
More Maize Diversity
Values for Top Lines Confirmed Independently in
Peter Beyer Lab
7
Vitamin A Equivalents - Best Inbreds CI.7
DE3 Versus Mo17 B73 Represents Typical
Corn
Shows Considerable Potential to Increase
ProVitaminA
8
  • -DE3 derived from Germplasm Enhancement Maize
  • GEM - Private/Public Cooperation to Increase
    Diversity in North American Maize
  • Pedigree Dekalb XL212 Hybrid x Coded Elite Non
    Stiff Stalk Elite Commercial Inbred. Then
    Derived Lines Selected at Delaware
  • Shows Competitive Grain Yield Equal to All
    Twelve Commercial Checks in First Evaluation Two
    Replicates on Our Research Farm 04
  • Provides Germplasm with Contemporary Yield
    Potential useful for Public Sector Breeders
  • Have Crossed DE3 with CI7, CML328 other lines
    with objective to increase ProVitaminA

9
- Can Concurrently Breed for ProVitamin A
Structures. Wish Slow Flux Through Hydroxylases
Lycopene
Correlations
0.28
a-carotene
b-carotene
0.56
0.51
b-crytptoxanthin
OH
OH
OH
0.81
Lutein
Zeaxanthin
OH
OH
10
Genetic Crosses - F1s - Show SC55 has Alleles
that Can Influence Flux Though Carotenoid
PathwayResulting in Higher Level Beta-Carotene
Basis May be Inhibitors or Weak Hydroxylase
Alleles Developed A619 x SC55 Mapping Population
- QTL
11
Carotenoid Profiles of NC354, TZI18 and
Reciprocal Crosses in F1 Seed
Previous Slide Shows Specific Lines Combine
Differently F1 This Shows Reciprocal Affects
for Combining for Carotenoids
12
QTL Analysis Suggests Candidate Genes A632 x
W64A F23s IHOxB73 BC1S1s
Y1 Phytoene Synthase
2.0
5.01
9.01
2.02
Y1

04
ZDS
?
8.05
3.06
5.05
10.05
4.08
5.07
10.07
2.09
ZDS Zeta Carotene Desaturase
X
VI
VII
VIII
II
III
IV
V
IX
I
Y1 and ZDS are in Carotenoid Biosynthetic Pathway
13
Y1SSR in Phytoene Synthase Candidate Gene Shows
Variation in Maize Diversity Lines
227bp-
-224bp
216bp-
210bp-
-204bp
Diversity Lines and Carotenoid Values Grouped by
Y1SSR Alleles Show an Initial Association with
Some Carotenoids
14
Means of Carotenoids for Y1ssr Marker Groups
Show Differences for BetaCarotene, Carotenoids
Groups include only yellow and orange, whites
excluded
15
Single Factor Analysis Comparisons of Two Sets of
Groups with Phenotypic Means Significant for
BetaCarotene Supports Candidate Gene PSY
16
African Breeders Able to Search for and Select
Best Phytoene Synthase Alleles within Adapted
Germplasm
GGPP
Lycopene
PSY
Phytoene
b- LCY
b- LCY e- LCY
PDS
2x
Phytofluene


a- carotene
z- carotene
b- carotene
ZDS
2x
Neurosporene
b-crytptoxanthin

Zeaxanthin
Lutein
Select Alleles at Other Genes
17
Other Genes in Carotenoid Biosynthetic Pathway-
Variation in Phytoene Desaturase and Zeta
Carotene Desaturase Readily Revealed -
ZDS
PDS
-PCR based Markers in Candidate Genes
Resolvable on Agarose Gels Attractive for LDC
Technology Transfer -Collaboration with DNA
Sequencing by Ed Buckler Lab -Systematically
Assay Pathway Genes for Association
18
Summary
  • Survey of diverse maize inbreds revealed
    considerable variation in Pro-Vitamin A
  • Certain lines combine better with other lines for
    ß-carotene in F1 seed
  • Genetic crosses alter flux through pathway
    resulting in higher levels of ß-carotene
  • Initial Candidate Gene Analysis with Phytoene
    Synthase Encouraging Sequencing
  • Results Indicate Breeding for Beta Carotene
    Should Make Progress. Since Not Attempted Before
    - Likely Exploit untapped potential

19
  • Acknowledgments
  • US Agency for International Development
  • Major Goodman NC State / Ed Buckler USDA/ARS now
    Cornell
  • Sultana Islam, Jeff Wong, Chandra Paul
  • HarvestPlus

20
Breeding for Higher
X
X
Near-Isogenic for Presence Absence
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