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In this work, 9 novel LMW-GS genes (6 LMW-m and 3 LMW-i type) from 4 diploid and 1 tetraploid Aegilops species were amplified and cloned by allelic-specific PCR. Analysis of the deduced amino acid sequences showed that 7 and 2 LMW-GS had 9 and 7 cysteines, respectively. Four LMW-m type subunits genes had an extra cysteine at the C-terminal III, which could form intermolecular disulphide bonds to extend the chains, and therefore would facilitate to form larger gluten polymers. This suggested that these genes are expected to be used as candidate genes for wheat quality improvement. The correlation between specific N-terminal sequences and a decapeptide deletion in the C-terminal II in LMW-GS encoded by D genome was found. Particularly, if LMW-GS possessed a METRCIPG-N-terminal beginning sequences and a decapeptide (LGQCSFQQPQ) deletion in the C-terminal II, they could be encoded by D genome.
., Simeone, M., Masci, S., Porceddu, E. 1997. Molecular characterization of a LMW-GS gene located on chromosome 1B an the development of primers specific for the Glu-B3 complex locus in durum wheat. Theor. Appl. Genet. 95 :1119
Singh, N.K., Shepherd, K.W., Cornish, G.B. 1991. A simplified SDS-PAGE procedure for separating LMW-GS. J. Cereal. Sci. 14 :203–208. Cornish G.B. A simplified SDS-PAGE procedure
Thirty bread wheat cultivars grown in Lesotho were analysed with sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). High and low molecular weight glutenin subunits (HMW-GS and LMW-GS) and gliadins were used to determine genetic variability and relationships between the cultivars. The HMW-GS could not distinguish the cultivars, while both LMW-GS and gliadins could. The Glu-1 score showed that all the quality classes from excellent to poor were represented in the material, but 11 cultivars had the highest score of 10, indicating excellent quality. Cluster analysis performed using gliadins in combination with LMW-GS generated dendrograms which segregated cultivars according to genetic distance. However, the genetic distance between the cultivars were so close that it could be concluded that they are from the same gene-pool and have been used several times in regional breeding programmes.
The effect of low molecular weight (LMW) glutenin subunits (GS) in presence of high molecular weight (HMW)-GS has over SDS sedimentation volume (SDSS) and kernel elasticity is presented. Twenty-six wheat lines having different origins and classified by SDS-PAGE into 14 different LMW-GS genotypic allelic groups were analyzed. When good HMW-GS background, i.e. Glu-1 1, 2*, 7 + 9 or 17 + 18 and 5 + 10 was associated with a number of allelic variants of Glu-3 loci (LMW-GS), i.e. Glu-A3 c and b; Glu-B3 g, h, d, higher kernel modulus of elasticity and SDSS were generally present. However, when poor HMW-GS background was present, i.e. Glu-1 null, 7 + 8, 2 + 12, a poor to medium modulus of elasticity and SDSS were generally found. Glu-B3 j allelic group, which possesses the wheat-rye translocation showed a tendency to have low elastic modulus, high plastic work (WP) and low SDSS. The effects of good LMW-GS are enhanced by a good HMW-GS background, yielding higher kernel elasticity and SDSS.
High molecular weight (HMW-GS) and low molecular weight (LMW-GS) glutenin subunits play a significant role in bread making quality and extensibility, though they signify merely 10% and 40% of the entire seed storage proteins. For the estimation of bread quality on the basis of allelic difference in HMW-GS and LMW-GS at Glu-1 and 3 loci, wheat germplasm (77 genotypes) was collected from diverse agro-climatic regions of Pakistan and characterized by using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Thirty distinct allelic arrangements were identified with a sum of thirteen Glu-1 alleles. Maximum frequency of allele 1 was found in twenty-nine genotypes at Glu-A1 locus while high proportion of subunit pairs 13 + 16 and 2 + 12 was detected in 33 and 32 genotypes at Glu-B1 as well as Glu-D1 locus, respectively. Few rare alleles were also separated out. The quality scores ranged from 4–10, however highest quality score of ten was more recurrent (36.36%). A good quality score of 8 and 6 were found in 32.47% as well as 19.48% of genotypes individually. In LMW-GS, seventeen diverse combinations of alleles with aggregate of ten Glu-3 alleles were detected. Glu-A3c and Glu-B3d alleles were observed in 33 (42.85%) genotypes, encoding high sedimentation and protein contents. Hence, this will enable the breeders to utilize both glutenin subunits as biochemical indicator for selecting superior wheat genotypes possessing enhanced bread making quality.
The dwarf-male-sterile wheat is unique to China and has been improved by introducing good germplasm. In order to clear the subunits background of Dwarf-Male-Sterile wheat, sodium dodecyl sulphate polyacrylamide-gel electrophoresis (SDS-PAGE) was used to detect the high and low molecular weight glutenin subunits (HMW-GS and LMW-GS) compositions in BC1F1, F2 and F3 generations from Dwarf-Male-Sterile wheat. Twenty-five alleles and 49 HMW-GS compositions at the Glu-1 loci were detected in different generations. Null and subunit 1 were mainly existed at Glu-A1 , and 7 + 8 and 7 + 9 were primarily detected at Glu-B1 in different generations. Subunit combination 5 + 10 mainly appeared in BC1F1, while 2 + 12 major presented in F2 and F3 generations. HMW-GS compositions null, 7 + 8, 5 + 10 and null, 7 + 9, 5 + 10 showed higher frequencies than other banding patterns, followed by null, 14 + 15, 5 + 10 and null, 7 + 9, 2 + 12 combinations. In addition, some rare subunit combinations such as 14 + 15, 13 + 16, 17 + 18, 4 + 12, 2 + 10 and 5 + 12 were found in different generations. Eighteen alleles and 51 LMW-GS compositions at Glu-3 loci were found in different generations. Glu-A3 a and Glu-B3 d showed higher frequencies than others among three generations. There were mainly a, b, c alleles at Glu-D3 . Thirty, 31 and 14 different combinations were detected in BC1F1, F2 and F3 populations, respectively. There were some good combinations such as A3 d/ B3 h, A3 d/ B3 d/ D3 a, A3 b/ B3 b/ D3 a, A3 a/ B3 d/ D3 a for different quality characteristics. So some desirable subunit combinations could be selected from different generations and new cultivars with good quality under distinct subunits background should be bred from Dwarf-Male-Sterile wheat in future.
The allelic variation for Glu-1, Glu-3 loci and presence of IBL-1RS translocation was determined in 126 spring wheat accessions. The most common alleles at Glu-1 loci were Glu-A1b (59.52%), Glu-B1c (41.26%), and Glu-D1d (57.14%) and at Glu-3 loci were Glu-A3c (56.45%), Glu-B3j (29.36%), and Glu-D3b (76.98%). Modern Pakistani wheat varieties carried superior alleles at Glu-1 and Glu-3 loci for bread-making quality and had no negative influence of secalin protein-synthesized by 1BL-1RS translocation. For LMW-GS, the most common combination was Glu-A3c, Glu-B3j and Glu-D3b. The loci Glu-B1 and Glu-B3 had the highest allelic diversity of Glu-1 and Glu-3 loci, respectively.
Two lines, L-19-613 and L-19-626, were produced from the common wheat cultivar Longmai 19 (L-19) by six consecutive backcrosses using biochemical marker-assisted selection. L-19 (Glu-D1a, Glu-A3c/Gli-A1?; Gli-A1? is a gene coding for unnamed gliadin) and L-19-613 (Glu-D1d, Glu-A3c/Gli-A1?) formed a set of near-isogenic lines (NILs) for HMW-GS, while L-19-613 and L-19-626 (Glu-D1d, Glu-A3e/Gli-A1m) constituted another set of NILs for the LMW-GS/gliadins. The three L-19 NILs were grown in the wheat breeding nursery in 2007 and 2008. The field experiments were designed using the three-column contrast arrangement method with four replicates. The three lines were ranked as follows for measurements of gluten strength, which was determined by the gluten index, Zeleny sedimentation, the stability and breakdown time of the farinogram, the maximum resistance and area of the extensogram, and the P andWvalues of the alveogram: L-19-613 > L-19-626 > L-19. The parameters listed above were significantly different between lines at the 0.05 or 0.01 level. The Glu-D1 and Glu-A3/Gli-A1 loci had additive effects on the gluten index, Zeleny sedimentation, stability, breakdown time, maximum resistance, area, P and W values. Although genetic variation at the Glu-A3/Gli-A1 locus had a great influence on wheat quality, the genetic difference between Glu-D1d and Glu-D1a at the Glu-D1 locus was much larger than that of Glu-A3c/Gli-A1? and Glu-A3e/Gli-A1m at the Glu-A3/Gli-A1 locus. Glu-D1d had negative effects on the extensibility and the L value compared with Glu-D1a. In contrast, Glu-A3c/Gli-A1? had a positive effect on these traits compared with Glu-A3e/Gli-A1m.
://www.aaccnet.org/grainbin/pdfs/II_HMW_Subunits.pdf Békés, F., Cavanagh, C.R., Martinov, S., Bushuk, W., Wrigley, C.W. 2006c. The Gluten Composition of Wheat Varieties and Genotypes. Part II. Composition table for LMW-GS. http://www.aaccnet.org/grainbin/pdfs/III_LMW Subunits
