Abstract
High molecular weight glutenin subunits (HMW-GSs) are key determinants for the end-use quality of wheat. Chinese wheat landraces are an important resource for exploring novel HMW-GS genes to improve the wheat baking quality. Two novel Glu-1Dy HMW-GSs (designated as 1Dy12.6 and 1Dy12.7) were identified and cloned from two Chinese wheat landraces Huazhong830 and Luosimai. The 1Dy12.6 and 1Dy12.7 subunits were deposited as the NCBInr Acc. No KR262518, and KR262519, respectively. The full open reading frames (ORFs) of 1Dy12.6 and 1Dy12.7 were 2022 bp and 1977 bp, encoding for proteins of 673 and 658 amino acid residues, respectively. Each contains four typical primary regions of HMW-GSs (a signal peptide, N- and C-terminal regions, and a central repetitive region). Their deduced molecular masses (70,165 Da and 68,400 Da) were strikingly consistent with those identified by MALDI-TOF-MS (69,985Da and 68,407 Da). The 1Dy12.6 is the largest 1Dy glutenin subunits cloned in common wheat up to date, containing longer repetitive central domains than other 1Dy encoded proteins. In comparison with the most similar active 1Dy alleles previously reported, the newly discovered alleles contained a total of 20 SNPs and 3 indels. The secondary structure prediction indicated that 1Dy12.6 and 1Dy12.7 have similar proportion of α-helix, β-turn, and β-bend to those of 1Dy10 (X12929). The phylogenetic analysis illustrated that the x- and y-type subunits of glutenins were well separated, but both 1Dy12.6 and 1Dy12.7 were clustered with the other Glu-1Dy alleles. Our results revealed that the 1Dy12.6 and 1Dy12.7 subunit have potential to strengthen gluten polymer interactions, and are valuable genetic resources for wheat quality improvement.
Highlights
Wheat (Triticum aestivum L.) is a significantly distinctive cereal crop by forming flour dough with visco-elastic properties that can be processed to produce a vast variety of foodstuffs such as steamed buns, cakes, biscuits, noodles, sour dough breads and pizzas
high molecular weight glutenin subunit (HMW-GS) profiles of the two Chinese wheat landraces were obtained by MALDI-TOF-MS (Fig 1)
The SDS-PAGE analysis showed that 1Dy12.7 possessed similar electrophoretic mobility to 1Dy12 in Chinese Spring; the mobility of subunit 1Dy12.6 from Huazhong830 was slower than that of the subunit 1Dy12 from Chinese Spring (Fig 2A)
Summary
Wheat (Triticum aestivum L.) is a significantly distinctive cereal crop by forming flour dough with visco-elastic properties that can be processed to produce a vast variety of foodstuffs such as steamed buns, cakes, biscuits, noodles, sour dough breads and pizzas. High molecular weight glutenin subunits with relative molecular masses ranging from 60,000 Da to 90,000 Da are key constituents in their ability to form wheat dough strength, substantially influencing the end-use quality of wheat flour for bread-making [16,17,18,19,20] In common wheat, they are encoded by Glu-1 loci located on the long arms of chromosomes 1A, 1B and 1D [21]. The y-type subunits generally exhibit relatively faster electrophoretic mobility on SDS-PAGE [20,21] Both x- and y-type subunits possess similar primary structures, containing a signal peptide, a non-repetitive N-terminal region, a nonrepetitive C-terminal region, and a long repetitive central region [22]. The y-type glutenin subunits possess more cysteine residues than xtype subunits, are capable of forming more inter- and intra-molecular disulfide bonds, which aggregate HMW-GSs with each other and with LMW-GSs, resulting in improving dough quality [25]
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