Steptoe x Morex – the weakest link?L Ramsay1, R Waugh1, D Marshall1, T Close2, G Young1, R Keith1 & W Thomas1

1SCRI, Invergowrie, Dundee DD2 5DA, UK; 2UCR, University of California, Riverside, CA 92521-0124, USA

Conclusions

Despite the major genes segregating in

both crosses, we were able to detect

some evidence of co-location of QTLs

for the same trait in the different crosses

but, despite the common environments

and marker assays, most of the

locations are cross-specific. Indeed, for

yield in SxM, many of the QTLs are

associated with various parameters of

harvest loss (see photographs), which

emphasise the need to work with the right

germplasm for the target environment.

Results

A third of the BOPA1 SNPs were polymorphic in DxB compared to just over

a half in SxM. Nevertheless, the DxB data enabled the location of just over a

third of the previously unmapped BOPA1 SNPs. In general, both populations

spanned similar genomic regions – DxB lacked coverage of the first 2 bins

and the first bin on chromosomes 2H and 5H respectively. SxM lacked

coverage on the last 7 bins of chromosome 6H and DxB had a completely

different haplotype on the long arm of 4H (Figure 1).

Over 100 bin x trait locations were detected over

the two crosses but there were only six instances

of the same trait being located in the same bin for

both crosses, although there were some in

adjacent bins (Figure 2). The co-locations were

for TGW in bin 5 and bin 7 on chromosomes 2

and 7H respectively, for yield in bin 10 on 4H, for

heading date and milling energy in bins 4 and 6

respectively on 7H and for grain width:length ratio

in bin 6 of 4H.

Materials & Methods

DH populations from SxM and DxB were grown at SCRI in each of harvest years

2002-4 inclusive, with each being sown on the same date and given the same

management regime. Plots were scored for heading date and height and harvested

when ripe to assess plot yield.

Cleaned and sieved samples were used to measure thousand grain weight (TGW by

MARVIN digital analyzer) and hardness (by Comparamill). The DxB population was

genotyped with the Illumina BOPA1 SNPs and a fresh marker map constructed that

included several key major genes. The SxM population had been genotyped with

pilot OPA1 and 2, data from which was used to construct BOPA1. We therefore

extracted the BOPA1 equivalent SNP polymorphisms from the pilot OPA1 & 2 data

to construct a new SxM map that was directly comparable to the DxB map.

Little spatial variation was apparent in the trials and so the unadjusted scores from

each trial in each year were used in QTL detection. QTL locations were then

referenced to the SxM bin map to compare locations.

AcknowledgementsWe thank the Scottish Government for their financial support of this work.

Whilst many single cross QTL studies have been conducted,

there are few examples that have compared the results from

two different crosses grown in the same environment and

with the same marker assay. Two of the most widely studied

barley crosses in QTL analyses are DH populations from

Steptoe x Morex (SxM), representing adapted North West

American germplasm, and Derkado x B83-12/21/5 (DxB),

representing adapted North West European germplasm.

The advent of the Illumina SNP genotyping platform means

that we can now readily generate marker maps from the

same platform and, given trials grown in the same

environment, compare results.

Introduction

1

Hor22

Hor1

34

5

6

78

Glb1

9

10

11

12

13

14

1H

1

2Ppd1

3

4

5

67

89

Vrs1

10

11

12

13

14

15

2H

1

2

3

4

5

6

78

9

10

11sdw112

13

14Glb4

15

16

3H

1

23

4Dhn6

5RubA

6

7

8

9

mlo10

11Vrn212

Bmy113

4H

1

23

45

ari-e

6

7

8

9

10

Vrn111

12

13

14

15

5H

1

2

34

5

6

7

8Amy1

9

10

111213

14

6H

1Wx

2

3

4

5

6

7Amy2

8

9

10

11

12

7H

16

1

Hor22

Hor1

34

5

6

78

Glb1

9

10

11

12

13

14

DxB

SxMDxB

SxMSxM

SxMSxM

1H

1

2Ppd1

3

4

5

67

89

Vrs1

10

11

12

13

14

15

SxMDxB

SxMSxM

DxB

DxB

SxM

SxMDxB

SxMDxB

SxMSxM

SxMDxB

SxMDxB

SxMSxM

2H

1

2

3

4

5

6

78

9

10

11sdw112

13

14Glb4

15

16

DxB

SxMDxB

SxMSxM

DxB

DxB

DxB

DxB

SxMSxM

SxMDxB

DxB

DxB

DxB

DxB

DxB

3H

1

23

4Dhn6

5RubA

6

7

8

9

mlo10

11Vrn212

Bmy113

SxMSxM

DxB

SxM

SxMDxB

SxMDxB

SxM

4H

1

23

45

6ari-e7

8

12

13

14

15

SxMDxB

SxMDxB

SxMDxB

SxMDxB

SxMDxB

SxM

DxB

DxB

5H

1

2

34

5

6

7

8Amy1

9

10

111213

14

DxB

DxB

SxMSxM

DxB

SxMSxM

SxM

6H

1Wx

2

3

4

5

6

7Amy2

8

9

10

11

12

DxB

SxMSxM

DxB

SxMSxM

DxB

SxMDxB

SxMDxB

SxMSxM

DxB

SxMSxM

SxMDxB

DxB

SxM

7H

Heading Date

Milling Energy

Width:Length

Height

Yield

TGW

Acknowledgements

DxB

SxM

t A

We ththeir f

12

13

14

15

DxB

DxB

SxM

8Amy1

9

10

111213

14

DxB

7Amy2

8

9

10

11

12

SxMSxM

DxB

ng Date

g Energy

Length

A

White: Not polymorphic in DxBRed: Not polymorphic in SxMGreen: Different haplotypes