The Composition Of Low Molecular Glutenin Subunit Genes In Common Wheat

Low-molecular-weight glutenin subunits are the major components of seedstorage proteins in common wheat, which is one of the key factors contributing todough viscoelastic properties. They play an important role in determining thebread-making quality of bread wheat.However, LMW-GS are encoded by a multi-gene family and has overlappingmobility with the abundant gliadin proteins. It is difficult to separate and identify all ofthe LMW-GS genes in one common wheat，especially in a mass population, by usingSDS-PAGE and other traditional methods.LMW-GS gene marker system is well made up for the shortage of originalmethords. This molecular marker system can accurately and efficiently identifyLMW-GS genes in common wheat. It also can be used to analyze the components ofLMW-GS genes in a mass population.In the present study, using the LMW-GS gene marker system, we investigate theChinese wheat germplasm2787(including cultivars, parents, landrace and someforeign varieties) and analyze the composition of their LMW-GS genes, the mainresults are as follows:1．In the Chinese important wheat germplasm, at least10LMW-GS genes wereidentified from one wheat variety.2．At the Glu-A3locus, two m-type genes and4i-type genes were identified. Allthe i-type genes are located at the Glu-A3locus. They are tightly linked formed12kinds of haplotypes in the Chinese important wheat germplasm. The number of thesewheats, which contain the haplotype A3-502/620, is most and accounte for58.42%.Second is the haplotype A3-484/565/568/662, accounting for26.85%. At the Glu-B3locus, we identified3m-type genes and3s-type genes. The s-type genes at the Glu-B3locus are also tightly linked and formed two main groups of haplotypes, one includeB3-621genes and the other incude B3-688genes. The two haplotypes,B3-544/578/621and B3-688/N, are the main haplotype in Glu-B3locus. At the Glu-D3locus, one m-type genes and7s-type genes were identified. LMW-GS genes at theGlu-D3locus are much conserved. We don’t find any linked genes.3．At the Glu-A3locus, there are20kinds of genotypes, with type5,14,15,19,20as the main genotype. At the Glu-B3locus, there are19kinds of genotypes, withtype1,2,11as the main genotype. At the Glu-D3locus, there are21kinds of genotypes, with type2,4,5,6as the main genotype.1BL/1RS translocation line has alarge proportion in the Chinese important wheat germplasm (44.21%), which illustratethat nearly half of our country’s wheat is1BL/1RS translocation lines.4．The domestic and foreign wheat materials are relatively consistent in thecomposition of LMW-GS genes. In the three loci, the genotypes of LMW-GS gene inGansu province are lower than other provinces, because the number of wheat in thisprovince is much least in the nine provinces. But the genotypes of LMW-GS gene inShandong, Henan, Hebei, Sichuan province are more than other provinces, whichillustrates the genotypes of LMW-GS gene in this provinces have greater geneticvariation. Compaired with the landrace varieties in the micro-core colleations ofChinese wheat germplasm,1BL/1RS translocation lines were not found in the landracevarieties. Some genotypes, which belong to the landrace varieties, were not found inthe Chinese important wheat germplasm. With the same genotypes, some genotypes’percentages are much higher than the landrace varieties, and the others are lower thanthe landrace varieties. These conclution indicate that: Based on the landrace varieties,the breeding of our wheat germplasm is experienced a system selection.5．At the Glu-A3locus, with i-type haplotype A3-502/646is inferior withnegative effects on quality propoties. But including i-type haplotypeA3-484/565/568/662is correlated with superior bread-making quality. At the Glu-B3locus, with genotypes B3-530/578/607/621、B3-530/578/544/621、B3-510/570/688/691are correlated with superior bread-making quality, whereas the genotype B3-530/688produced inferior quality properties. The LMW-GS genes at the Glu-D3locus are nosignificant differences in quality proterities.6．It’s further confirmed that the LMW-GS gene marker system is very perfect,and can be used to analyze all over of the world wheat’s LMW-GS genes composition.From all the above-mentioned results, we not only prove the LMW-GS genemarker system has a great deal of value and practical significance in isolating andidentifying LMW-GS genes, but also definite the compositions of LMW-GS genes inour county’s wheat germplasm, which can provide some reference to improve thequality in bread wheat.