Amino acid analysis of GEM germplasm

M. Paul ScottUSDA-ARSAmes, Iowa 50011

pscott@iastate.edu

U.S. Corn UsesNational Corn Growers Association, 2004

Annual value:$25 Billion

Impact of increased ethanol production

Corn Prices UpCorn Acres UpSoybean price DownGov’t Payments DownLivestock income Slight decreaseOverall Farm income UpN, P Lost to water UpSoil Erosion Up

Source: WRI policy note,2006 Marshall & Greenhalgh

Annual meat consumption, per capita(Source: FAO)

0

20

40

60

80

100

120

140

19

61

19

65

19

69

19

73

19

77

19

81

19

85

19

89

19

93

19

97

Year

kg United States

World average

Food and Fuel

Transportation Feed

PetroleumGrain

hydrocarbons Starch Protein Oil

Oilseeds

Protein Oil

Food

Food and Fuel

Transportation

Petroleum

Feed

Grain

Starch Protein Oil

Oilseeds

Protein Oil

Food

146 Billion GallonsGasoline used/year in US

3.9 Billion GallonsEtOH in 2005

13% of Corn crop

A solution

Transportation

Petroleum

Feed

Grain

Starch Protein Oil

Oilseeds

Protein Oil

Food

LignocellulosicBiomass

Grain +Ethanol Co-products:DDGs

What corn traits are important?

• Yield (insect, disease, drought …)• N use efficiency

• What about quality traits?

2.7 gal/bu$4.32/bu

18 lb/bu$0.68/bu

Corn

Co-products:DDGS,

Solubles

Grain Ethanol Production

Protein 30%Fiber 10-50%Fat 10-20%Starch 5%

Protein 10%Fiber 3%Fat 4%Starch 75%

EtOH

Starch

Protein,Fiber,Fat

Protein is concentrated by ethanol production!

Problems are amplified!

Seed FractionationOsborn, 1924

Water

Albumins

Salt

Globulins

Alcohol

Prolamins“Zeins”

Base

Glutelins

Seed Proteins

Embryo-vegetative Endosperm-storage

Zeins

SDS-PAGE Coomassie Blue Stained

Zeins

• Zeins are so abundant that they have a large impact on protein quality of grain

• Zeins are concentrated in ethanol co-products so their impact is even greater

• Zeins are nutritionally poor for non-ruminants– They are poorly digested– They are deficient in certain essential amino

acids

Amino acid levelsCorn vs. Egg

0

0.5

1

1.5

2

2.5

Lys His Arg Asx Thr Ser Glx Pro Gly Ala Cys Val Met Ile Leu Tyr Phe Trp

MaizeSoy

Methionine is the limiting AA in Poultry diets

Lysine is limiting in poultry and swine diets, but can be supplemented inexpensively

Tryptophan is limiting in swine diets

Nutritionally limiting amino acids

What corn traits are important?

• Yield (insect, disease, drought …)

• N use efficiency

For Ethanol:•Fermentable starch•Protein quality•Available P

For non-ruminant feed:•Protein content •Protein quality•Available P

Amino acid/ protein

Absolute amino acid level

Questions about biofuel co-products

• How are differences in grain composition reflected in co-product composition?

• How will co-products be improved by processing?

• Can yeast components be used to complement grain components in co-products?

Evaluation of amino acid content of GEM germplasm

• About 80 GEM accessions / year selected for agronomics and past AA performance.

• Good lines are re-tested in subsequent years

• Lys, Met, Trp, Index (Lys,Met,Trp)• Checks:

– B101 (high Met)– B45o2 (high Lys, Trp)– B73xMo17, B73, Mo17, B45

Microbial assay for Met

HighHigh LowLow

Met ConcentrationMet Concentration

Evaluation of amino acid composition of GEM germplasm

0.10

0.15

0.20M

0.010

0.015

0.020

M/p

rote

in

Two year Evaluation

0.08

0.10

0.12

0.14

0.16

0.18

0.20

M

0.006

0.008

0.01

0.012

0.014

0.016

M/p

rote

in

Evaluation of amino acid composition of GEM germplasm

Four year evaluation

Highlights of the GEM AA program

• DKXL212:N11a-139 Index was significantly higher than B73xMo17 in 4 yr tests.

• CHIS740:S1411a-783-2 Met/protein was not significantly different that hi met check and significantly higher than other checks in 4 yr tests

• Seven XL370 and XL380 derived lines were not different than high met check in 2 yr evaluations.

Recommendations

• Evaluation of hybrids

• Selection within GEM “lines”

• Development of synthetics for recurrent selection

Divergent selection for amino acid content

Long-term Selection f or protein content

Source: Dudley and Lambert (2004), Plant Breeding Source: Dudley and Lambert (2004), Plant Breeding Reviews 24, 79Reviews 24, 79--110110

Advantages:

Differences are magnified by selection in both directions

Generate unique material to answer biological questions

Recurrent Selection

BS31BS31HM

Selections(5 ears)

Evaluation of 50 ears

Intermating of Selections

BS31HM C1

BS31HM C1 Selections

(5 ears)

BS31HM C2

Divergent selection for AA Content

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13M

(g

/10

0g

)

-4 -3 -2 -1 0 1 2 3 4Cycle

0.08

0.09

0.1

0.11

0.12

0.13

0.14

0.15

M (

g/1

00

g)

-4 -3 -2 -1 0 1 2 3 4Cycle

0.006

0.007

0.008

0.009

0.01

0.011

0.012

0.013

W (

g/1

00

g)

-4 -3 -2 -1 0 1 2 3 4Cycle

0.006

0.007

0.008

0.009

0.01

0.011

0.012

0.013

W (

g/1

00

g)

-4 -3 -2 -1 0 1 2 3 4Cycle

BS11 BS31

Acknowledgements

• Mike Blanco and the GEM team

• Merinda Struthers

• Funding from

USDA-ARS project funds

Thanks for your attention!