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The high-molecular-weight glutenin subunits (HMW-GS) at Glu-D1 have a larger contribution to the processing property of wheat flours than those at the Glu-A1 and Glu-B1 loci and are always expressed in nature. Wheat lines missing one subunit at Glu-D1, either x or y, attract great interest for their potential quality value. Major quality parameters including SDS-sedimentation value, gluten-related indices, and other dough strength parameters such as development time, stability time, degree of softening, and farinograph quality numbers were tested in wheat lines solely expressing HMW-GS 1Dy12 from different backgrounds and compared with a weak gluten wheat control CN 16 to elucidate their quality potential. Wheat line solely expressing HMW-GS 1Dy12 derived from different genetic backgrounds showed similar but low SDS-sedimentation values (∼10 mL) and low wet gluten (∼20–25 g) and dry gluten contents (∼10 g). Additionally, wheat line solely expressing HMW-GS 1Dy 12 also showed a lower development time (<1 min), stability time (<1 min), and farinograph quality number (∼5–15), and a higher degree of softening (∼170–301), than the control CN 16. Wheat line solely expressing HMW-GS 1Dy 12 had a weak dough strength and may be used as a potential material for producing weak-gluten foods. [ABSTRACT FROM AUTHOR]

Low molecular weight glutenin subunits (LWM-GSs) play a crucial role in determining wheat flour processing quality. In this work, 35 novel LMW-GS genes (32 active and three pseudogenes) from three Aegilops umbellulata (2n = 2x = 14, UU) accessions were amplified by allelic-specific PCR. We found that all LMW-GS genes had the same primary structure shared by other known LMW-GSs. Thirty-two active genes encode 31 typical LMW-m-type subunits. The MZ424050 possessed nine cysteine residues with an extra cysteine residue located in the last amino acid residue of the conserved C-terminal III, which could benefit the formation of larger glutenin polymers, and therefore may have positive effects on dough properties. We have found extensive variations which were mainly resulted from single-nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) among the LMW-GS genes in Ae. umbellulata. Our results demonstrated that Ae. umbellulata is an important source of LMW-GS variants and the potential value of the novel LMW-GS alleles for wheat quality improvement. [ABSTRACT FROM AUTHOR]

Key message: This study provides a link between a de novo gene and novel phenotype in wheat-rye hybrids that can be used as a model for induced de novo genetic variation. Abstract: Wide hybridization can produce de novo DNA variation that may cause novel phenotypes. However, there is still a lack of specific links between changed genes and novel phenotypes in wide hybrids. The well-studied high-molecular-weight glutenin subunit (HMW-GS) genes in tribe Triticeae provide a useful model for addressing this issue. In this study, we investigated the feasibility of a wheat-rye hybridization method for inducing de novo phenotypes using the Glu- 1Dx2.2 subunit as an example. We developed three hexaploid wheat lines with normal fertility and a Glu- 1Dx2.2 variant, named Glu- 1Dx2.2, derived from three F hybrids. The wild-type Glu- 1Dx2.2 has two direct repeats of 295 bp length separated by an intervening 101 bp in its central repetitive region. In the mutant Glu- 1Dx2.2, one copy of the repeats and the intervening sequence were deleted, probably through homology-dependent illegitimate recombination (IR). This study provides a direct link between a de novo allele and novel phenotype. Our results indicate that the wheat-rye method may be a useful tool to induce de novo genetic variations that broaden the genetic diversity for wheat improvement. [ABSTRACT FROM AUTHOR]

Three y-type high-molecular-weight (HMW) glutenin gene open reading frames (ORFs), Chiy1, Chiy2, and Racy, were isolated and characterized from Leymus chinensis PI499516 and Leymus racemosus ssp. racemosus W623305. They shared an extra glutamine in the N-terminal and LAAQLPAMCRL peptides in the C-terminal with x-type HMW glutenins but had different N-terminal lengths. Like other y-type HMW glutenins, Chiy2 and Racy had 104 (or 105) amino acid (aa) residues at the N-terminal and started with EGEASR, whereas Chiy1 had 99 aa in this domain and started with QLQCER because of the deletion of EGEASR. Five other y-type glutenins, including those from Elymus ciliaris, Pseudoroegneria libanotica, and Leymus mollis, were similar to Chiy1. The ORF of Chiy2 was probably not expressed. The ORFs of both Chiy1 and Racy were expressed in bacteria. The maximum likelihood phylogenic tree based on the signal peptide and N-terminal and C-terminal aa residues revealed two clades of y-type HMW glutenins in Triticeae; the first contained Ay, By, Cy, Dy, Eey, Gy, Ky, Ry, Tay, and Uy, while the second clade contained the remaining y types, including those from Leymus. Within the second clade, HMW glutenins lacking the EGEASR peptide formed a subclade. These y-type HMW glutenins in Leymus could not be targeted to the Xm or Ns genome. [ABSTRACT FROM AUTHOR]

High-molecular-weight glutenin subunits (HMW-GS) determine the elasticity of wheat dough. The null HMW-GS alleles had potential value in modifying the end-use quality of weak gluten wheat. The quality of wheat lines with triple null alleles at the Glu-1 locus (3 N lines) was tested and compared with non-3 N controls. Most 3 N lines had significantly higher protein content, degree of softening, and ratios of low-molecular-weight glutenins (LMW-GS) to glutenins than the non-3 N controls. The 3 N lines had significantly lower Zeleny-sedimentation values, gluten-related indices, and development and stability times; lower contents of LMW-GS and glutenins; and lower ratios of glutenin to gliadin than the non-3 N lines. The contents of the gliadin fractions of the 3 N lines were close to or even higher than those of the non-3 N lines. These results suggest that the 3 N lines had weaker gluten strength than the non-3 N flours. Two 3 N flours were blended with five base flours to test their effects on biscuit quality. Blending the 3 N flours with five base flours at certain ratios could improve some biscuit quality indices, such as increase the slice area and the extensibility factor and decrease the thickness of biscuit. The 3 N flours could be used to improve the biscuit-making quality. [Display omitted] • Quality of wheat with triple null alleles at the Glu-1 locus (3 N lines) was tested. • The 3 N lines had weaker gluten strength than the non-3 N flours. • The 3 N lines had significantly lower values in major quality parameters than the non-3 N lines. • The 3 N lines had significantly lower glutenin/gliadin ratio and glutenin contents than the non-3 N lines. • Blending the 3 N flours with base flours at certain ratios could could enlarge the size and reduce the thickness of biscuit. [ABSTRACT FROM AUTHOR]

Abstract: Three HMW-GS and the respective ORFs from diploid species Eremopyrum distans and Eremopyrum triticeum were characterized. Compared to homologous proteins, they showed novel modifications in all domains. In the N-terminals, the y subunit from Er. triticeum (Xey) had 98 aa residues. A short G/IIFWGTS peptide deletion was responsible for the reduced number of aa residues. The end peptide in the y subunit from Er. distans (Fy) was IPTLLR. This unique structure was involved in a replacement between x types with IPA/TLLK/R and y types with R/TSSQTVQ. Both y subunits share the same short peptide LAAQLPAMCRL as x types in the C-terminals. Phylogenic relationships among orthologous genes from Triticeae species revealed that Fy and Xey were neither purely x type nor purely y type based on the N and C terminal residues. Divergence times indicated that Glu-Xe1 and Glu-F1 were separated from each other and that Glu-Xe1 separated from orthologous loci of wild wheat relatives earlier than Glu-F1. Based on the divergence times among Glu-F1, Glu-Xe1, Glu-O1, Glu-St1, and Glu-Ta1, it is possible that genome F separation from O, St, and Ta in species of Henrardia persica, Pseudoroegneria stipifolia, and Taeniatherum crinitum was more recent than the separation of F and Xe. [Copyright &y& Elsevier]