Abstract
The low-molecular weight glutenin subunit (LMW-GS) composition of wheat (Triticum aestivum) flour has important effects on end-use quality. However, assessing the contributions of each LMW-GS to flour quality remains challenging because of the complex LMW-GS composition and allelic variation among wheat cultivars. Therefore, accurate and reliable determination of LMW-GS alleles in germplasm remains an important challenge for wheat breeding. In this study, we used an optimized reversed-phase HPLC method and proteomics approach comprising 2-D gels coupled with liquid chromatography–tandem mass spectrometry (MS/MS) to discriminate individual LMW-GSs corresponding to alleles encoded by the Glu-A3, Glu-B3, and Glu-D3 loci in the ‘Aroona’ cultivar and 12 ‘Aroona’ near-isogenic lines (ARILs), which contain unique LMW-GS alleles in the same genetic background. The LMW-GS separation patterns for ‘Aroona’ and ARILs on chromatograms and 2-D gels were consistent with those from a set of 10 standard wheat cultivars for Glu-3. Furthermore, 12 previously uncharacterized spots in ‘Aroona’ and ARILs were excised from 2-D gels, digested with chymotrypsin, and subjected to MS/MS. We identified their gene haplotypes and created a 2-D gel map of LMW-GS alleles in the germplasm for breeding and screening for desirable LMW-GS alleles for wheat quality improvement.
Highlights
Gluten proteins comprise 70−80% of the total wheat flour protein; give wheat dough its unique viscoelastic properties; and make it possible to produce bread, pasta, noodles, and other products [1,2]
We found that the annotation of 24 low-molecular weight glutenin subunit (LMW-GS) spots in the 2-DGE of ‘Aroona’, Aroona’ near-isogenic lines (ARILs), and standard wheat cultivars did not match that from our previous study on LMW-GS alleles in standard wheat cultivars and Korean wheat cultivars [23]
To evaluate the dough-processing qualities of wheat cultivars, LMW-GS alleles at the Glu-3 loci have been ranked for dough strength in wheat cultivars from Australia [25] and New Zealand [29] and for the ‘Aroona’ near-isogenic lines (ARILs) [19,31]
Summary
Gluten proteins comprise 70−80% of the total wheat flour protein; give wheat dough its unique viscoelastic properties; and make it possible to produce bread, pasta, noodles, and other products [1,2]. Most genes encoding LMW-GSs in groups B, C, and D are located close to the Gli-1 loci encoding γand ω-gliadin on the short arms of group 1 chromosomes [15]. Some LMW-GSs in the C-group are located near the Gli-2 loci encoding α/β-gliadin on the short arms of group 6 chromosomes [16]. The close location of Gli-1/-2 encoding gliadin and Glu-3 encoding C/D-group LMW-GSs and their frequent recombination make analyzing the gene structure and function of LMW-GSs difficult [17,18]. To identify LMW-GSs corresponding to different alleles encoded by the Glu-A3, Glu-B3, and Glu-D3 loci, we fractionated glutenins from ‘Aroona’, a set of 12 ‘Aroona’ near-isogenic lines (ARILs) containing unique LMW-GS alleles in the same genetic background, and a set of 10 standard wheat cultivars. The results will be used to identify LMW-GS alleles in germplasm prior to breeding and to screen for desirable LMW-GS alleles for wheat quality improvement
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