Genomic Analyis of Seed Quality Traits in Corn

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• HarvestPlus Program
• Micronutrient Biofortification of Staple Crops
• zinc, iron, and Pro-vitamin A (carotenoids)
• One of Grand Challenge Programs
• Add Nutritional value to Crops
• Food as a mechanism to improve
• Human Health
• (Contrast to Corn Grain to Fatten Animals)

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• Survey Carotenoid (Pro-vitamin A)
• Variability in Maize
• Facilitate Breeding for Higher
• levels of Pro-Vitamin A for Human
• Nutrition

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Carotenoid Biosynthetic Pathway
GGPP
Lycopene
PSY
y1
Phytoene
b- LCY
b- LCY e- LCY
PDS
2x
Phytofluene
vp5
z- carotene
a- carotene
b- carotene
ZDS
2x
Neurosporene
b-crytptoxanthin
vp9
Zeaxanthin
Lutein
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HPLC Chromatogram 450 nm
Zeaxanthin
AU
Lutein
AU
ß-cryptoxanthin
a-carotene
ß-carotene
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Breeding for Higher Levels Beta-CaroteneSurveyin
g Diverse Germplasm Materials Developed at
IllinoisMaking Genetic CrossesCreating
Synthetics
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Means and Ranges from 2002 Survey
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Heritability/Repeatability Estimates
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Means and Ranges from 2003 Survey New and Wider
Set of Lines
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Candidate Pro-Vit A Lines
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Vitamin A Equivalents from CI.7, DE3, Mo17 and B73
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Chemical Structure of Vitamin A and Pro-vitamin A
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Carotenoid Biosynthetic Pathway
GGPP
Lycopene
PSY
y1
Phytoene
b- LCY
b- LCY e- LCY
PDS
2x
Phytofluene
vp5
z- carotene
a- carotene
b- carotene
ZDS
2x
Neurosporene
b-crytptoxanthin
vp9
Zeaxanthin
Lutein
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Correlation between a-carotene, ß-carotene,
ß-cryptoxanthin, lutein and zeaxanthin in 2002
and are significant at p lt.01 and p lt.0001,
respectively. ns, not significant at p lt.01
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, significant p lt .0001
Lycopene
a-carotene
b-carotene
0.56
0.51
b-crytptoxanthin
OH
OH
OH
0.81
Lutein
Zeaxanthin
OH
OH
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Lycopene
a-carotene
b-carotene
b-crytptoxanthin
OH
OH
OH
Lutein
OH
Zeaxanthin
OH
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Carotenoid Profiles of the SC55 Crosses
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Carotenoid Profiles of NC354, TZI18 and their
Reciprocal Crosses
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Develop Near-Isogenic Populations for High
Levels vs. Nil Beta-Carotene For BioEfficacy
Feeding Trials- Africa, Model Animals
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Breeding for Higher
X
X
Near-Isogenic for Presence Absence
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Gurnsey vs. HolsteinDifferent Levels Milk
FatCould Compare, But Maybe Other Micronutrient
Differences in the Milk
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So Cross Gurnsey vs. HolsteinCreate New
Gurnstein BreedSib Inbreed - Then Select for
Sisters Hi and Low for Just Milk
FatMicronutrients - Similar
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Creation of Near-Isogenic MaizeA619 x R30YY x
yyYy F1 YY, Yy yy F2sTake Pools of YY,
yyNormalize Genetic Background
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Develop Molecular Markers to Enhance Breeding for
Beta-CaroteneDNA Based Markers Because We are
Lazy and Cheap OR. Wish to make progress for
higher levels faster, more efficiently
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Vitamin Extraction
16 Samples Extracted in Two Hours
Extract Upper Layer
Heat 5min at 90 C
2X
Hexane (Extraction)
Heat 10 min at 90 C
dH20
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Major QTL Positions for Carotenoids A632 x W64A
F23s IHOxB73 BC1S1s
Y1 Phytoene Synthase
2.0
5.01
9.01
2.02
Y1

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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
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Carotenoid Biosynthetic Pathway
Lycopene
PSY
GGPP
y1
Phytoene
b- LCY e- LCY
b- LCY
PDS
Phytofluene
vp5
z- carotene
a- carotene
b- carotene
ZDS
Neurosporene
b-crytptoxanthin
vp9
Zeaxanthin
Lutein
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Determining Value of Y1SSR Marker from a
Candidate Gene we think is involved Good For
Technology TransferEncouraging. Sequence
Fragments for Associative Analysis Nucleotide
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Gel image of Y1ssr marker
227bp-
-224bp
216bp-
210bp-
-204bp
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Means of Groups using the fragment sizes of Y1ssr
marker
groups include only yellow and orange lines
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Multiple Regression of Means Y1ssr Marker Groups
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Single Factor Analysis among three groups and
their marker means
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Summary

• Survey of diverse maize inbreds revealed
  considerable variation in carotenoids and vitamin
  A equivalents
• Certain lines appear to combine better with other
  lines for ß-carotene and total carotenoids in F1
  seed

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• An initial candidate gene association analysis
  approach with y1ssr may be revealing an
  association between phytoene synthase and total
  carotenoids and ß-carotene
• TLC assays may enable a rapid screen of
  germplasm enabling identification of the top 20
  to keep and analyze by HPLC

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• Acknowledgments
• Sultana Islam, Chandra Paul, Jeff Wong
• US AID
• Your Thoughts and Questions and Input.