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Molecular Markers for Selected Quality Traits in Australian Hexaploid Bread Wheat

Adele L. Schmidt1*, Chunji Liu1, David Martin2, Allison Kelly2 and Lynne McIntyre1

1CSIRO Plant Industry, Queensland Bioscience Precinct, 306 Carmody Road, St Lucia, Brisbane 4067, Australia.
2
Queensland Department of Primary Industries and Fisheries, Leslie Research Centre, PO Box 2282, Toowoomba, Queensland 4350, Australia.
*
Corresponding author: Adele.Schmidt@csiro.au

Abstract

This paper reports results of a three-year study aimed at the identification of molecular markers for key quality traits specific to the Australian Northern Region. Using Australian germplasm, we have identified molecular markers for milling yield, water absorption, flour colour and specialised dough development properties required for expansion into markets where sponge and dough style baking dominates. Novel marker-trait associations were identified for milling yield, dough strength and dough development time. A novel sponge and dough QTL has been located on chromosome 4B and work is currently underway to refine the genetic map and further characterise this locus.

Media summary

Wheat quality is a subjective, complex trait, with many different components determined by the growing environment and the target market. We report findings of a three-year study that will allow wheat breeders to develop varieties via marker-assisted selection, with characteristics required for expansion into new markets.

Keywords

Wheat quality, milling yield, flour colour, dough strength, dough development, sponge & dough baking.

Introduction

The market value of wheat grain is determined by various factors. Wheat quality is a subjective, complex trait, with many different components determined by the growing environment and the target market. For Australian wheat growers, traits of interest include both broadly useful characteristics (e.g. milling yield and dough strength) and more specialised traits associated with key markets (e.g. flour colour requirements for the Asian noodle market). Previous studies have resulted in identification of molecular markers for many general interest traits such as milling yield (Parker et al. 1999), flour colour (Parker et al. 1998; Mares & Campbell 2001), protein content (Olmos et al. 2003) and dough strength (Metakovsky et al. 1997), and implementation of these markers in Australian breeding programmes will provide many benefits for growers. However, not all previously identified markers will be suitable for use in Australian germplasm, and some traits targeted within Australian breeding programmes will be unique to specific growing regions and intended markets.

This paper reports results of a three-year study aimed at the identification of molecular markers for key quality traits specific to the Australian Northern Region, as identified through consultation with the industry’s premier research and development body, the Grains Research and Development Corporation of Australia. Using Australian germplasm, we have identified molecular markers for: a) general quality traits such as milling yield, water absorption and flour colour and; b) specialised dough development properties required for expansion into markets where sponge and dough style baking dominates.

Materials and Methods

A genetic linkage map consisting of 140 microsatellite markers was constructed for a single doubled haploid (DH) (Kukri x Janz) population segregating for the traits of interest. Microsatellite markers used in map construction were originally isolated and characterised by Rder et al. (1998), Pestsova et al. (2000), Song et al. (2002), or the International Wheat Microsatellite Consortium (Varshney et al. 2000). Phenotypic data for each of the 180 progeny has been generated across two consecutive growing seasons (2001, 2002), with two field replicates (Biloela, central western Queensland, ~600km NW of Brisbane and Lundavra, southern Queensland, ~400km SW of Brisbane) in each season, but at the time of writing, data from one year only is available for analysis.

Traits measured include: a) milling yield; b) flour colour (including both b and L measures); c) water absorption; d) dough strength; e) dough extensibility; f) dough development time and; g) sponge and dough baking quality. All phenotypic data was generated within Queensland Department of Primary Industries laboratories, following methods described in Smith et al. (2001) (milling yield, water absorption), Mares and Campbell (2001) (flour colour), Parker et al. (1998) (flour colour) and Hareland and Puhr (1998) (sponge and dough).

Initial statistical analysis of marker-trait relationships was undertaken via simple marker-trait regression, using a skeletal map of 4-6 markers/chromosome. This approach allowed preliminary identification of relationships between chromosomes and traits. Additional markers are now being added to chromosomes of interest and once generation of the second year’s phenotypic data is complete, composite interval mapping will be used to refine QTL locations and provide more comprehensive, robust marker-trait relationships that can be exploited in marker-assisted selection programmes. All statistical analyses were conducted using QTL Cartographer for Windows Version 2.0 (Wang et al. 2003).

Results and Discussion

Preliminary analyses have revealed novel marker-trait associations for milling yield, flour colour, dough strength, dough development time and sponge and dough baking quality (Table 1). The presence of known gliadin and/or glutenin loci (Metakovsky et al. 1997) however, has not yet been taken into account and, for some traits (e.g. milling yield, dough development time), this is likely to be a confounding factor. Upon receipt of the second year’s phenotypic data, more comprehensive analysis can be undertaken, with the effects of these loci removed from the data set. This will allow clarification of results prior to implementation of marker-assisted selection programmes.

Preliminary analyses have also identified a strong putative QTL for sponge and dough baking quality (LRS = 19.7, p = 0.000), located on chromosome 4B. This locus accounts for 13% of phenotypic variation and, although further analysis using a second year’s phenotypic data is required to refine the marker-trait relationship and pinpoint QTL location, there are no published reports of confounding traits in the same genomic region and it is likely that the new locus will be of benefit for breeding programmes targeting the sponge and dough market.

Molecular markers for quality traits identified by simple marker-trait regression analysis in the Kukri x Janz (n=180, doubled haploid) population. Chromosomal locations (C’some) reported in previous studies are marked with an asterisk (*). Results of regression analysis are presented as likelihood ratio scores (LRS), with exact p-values (p) and percentage of phenotypic variation explained by marker genotype (%Var.). Results are recorded as being detected in one or both field sites (Site) and individual markers (Marker) showing strongest association with each trait are identified as published in Rder et al. (1998), Pestsova et al. (2000), Song et al. (2002) or Varshney et al. (2000). Note that the presence of known gliadin and glutenin loci on chromosomes 1A, 1B, 1D and 6B has not been taken into account in preliminary analysis. After obtaining a second year’s phenotypic data for each field location, composite interval mapping will be used to further refine marker-trait relationships.

Table 1: Molecular markers for Quality Traits in Kukri x Janz

Trait

C’some

LRS

p

% Var.

Site

Marker

Yield

1B
2D*
3A*
4B
6D

25.9
28.2
23.4
14.2
20.0

0.00000
0.0000
0.0000
0.004
0.0000

28
18
14
13
13

Biloela & Lundavra
Biloela & Lundavra
Lundavra
Biloela
Biloela & Lundavra

Xgwm11
Xgdm5
barc76
Xgwm192
barc29

Water absorption

1A*

22.8

0.00000

16

Biloela

Xgwm136

Colour b

3A
4B*

7.8
12.9

0.0053
0.0003

5
12

Biloela & Lundavra
Biloela & Lundavra

Xgdm3
Xgwm192

Colour L

4B*

5.2

0.0233

5

Lundavra

barc20

Dough strength

1B*
1D*
3A
3B

39.2
32.8
14.1
12.0

0.00000
0.00000
0.00018
0.0005

26
24
10
8

Biloela
Biloela
Biloela & Lundavra
Biloela & Lundavra

Xgwm11
Xgwm126
Xgdm38
Xgwm533

Dough development time

1B
2B
3A

31.0
9.4
10.3

0.00000
0.0022
0.00137

21
9
7

Biloela
Lundavra
Biloela

Xgwm11
Xgwm282
Xgwm191

Sponge and dough quality

4B

19.7

0.000

13

Lundavra

Xgwm495

Conclusion

Using Australian germplasm, we have identified molecular markers for key quality traits specific to Australia’s Northern Wheat Growing Region. Novel markers were identified for milling yield, dough strength and dough development time, although some of these marker-trait associations are complex and unravelling interactions between traits will require further analysis. A novel sponge and dough QTL has been located on chromosome 4B and work is currently underway to refine the genetic map and further characterise this locus so that it may be utilised in selection and breeding programmes.

Acknowledgements

This work is funded by a grant from the Grains Research and Development Corporation (GRDC) of Australia. The authors are indebted to members of GRDC, and to colleagues within both the Australian Winter Cereal Molecular Marker Programme (AWCMMP) and the Northern Region Molecular Marker Programme (NRMMP), for invaluable advice, support and shared resources.

References

Hareland, G. A. and D. P. Puhr (1998). Baking performance of durum and soft wheat flour in a sponge-dough breadmaking procedure. Cereal Chemistry 75: 830-835.

Mares, D. J. and A. W. Campbell (2001). Mapping components of flour and noodle colour in Australian wheat. Australian Journal of Agricultural Research 52: 1297-1309.

Metakovsky, E. V., Branlard G., Chernakov, V. M., Upelniek, V. P., Redaelli, R., Pogna, N. E. (1997). Recombination mapping of some chromosome 1A-, 1B-, 1D- and 6B-controlled gliadins and low-molecular-weight glutenin subunits in common wheat. Theoretical and Applied Genetics 94: 788-795.

Parker, G. D., K. J. Chalmers, Rathjen, A. J., Langridge, P. (1998). Mapping loci associated with flour colour in wheat (Triticum aestivum L.). Theoretical and Applied Genetics 97: 238-245.

Parker, G. D., K. J. Chalmers, Rathjen, A. J., Langridge, P. (1999). Mapping loci associated with milling yield in wheat (Triticum aestivum L.). Molecular Breeding 5: 561-568.

Pestsova, E., Ganal, M.W., Roeder, M.S. (2000). Isolation and mappng of microsatellite markers specific for the D genome of bread wheat. Genome 43: 689-697.

Rder, M. S., Korzun, V., Gill, B., Ganal, M.W. (1998). The physical mapping of microsatellite markers in wheat. Genome 41: 278-283.

Smith, A. B., B. R. Cullis, et al. (2001). The statistical analysis of quality traits in plant improvement programs with application to the mapping of milling yield in wheat. Australian Journal of Agricultural Research 52: 1207-1219.

Song, Q. J., Fickus, E.W., Cregan, P.B. (2002). Characterization of trinucleotide SSR motifs in wheat. Theoretical and Applied Genetics 104: 286-293.

Varshney, R. K., A. Kumar, Balyan, H.S., Roy, J.K., Prasad, M., Gupta, P.K (2000). Characterization of microsatellites and development of chromosome specific STMS markers in bread wheat. Plant Molecular Biology Reporter 18: 5-16.

Wang, S., Basten, C.J., Gaffney, P., Zeng, Z.B. (2003) Windows QTL Cartographer Version 2.0. Statistical Genetics, North Carolina state University, USA.

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