Allelic Variation And Molecular Markers Of HMW-GS In Wheat-Th. Intermedium Introgression Lines

The wheat storage proteins, especially the types and composition of high molecular weight glutenin subunits (HMW-GS), play important roles in the determination of flour processing and bread-making quality. However, the number of HMW-GS alleles with good processing quality is limited in bread wheat cultivars, while there are plenty of HMW-GS alleles in wheat-related grasses to exploit. Th. intermedium (2n=6x=42) of the Thinopyrum species carries many useful agronomic traits such as high content of seed protein and high resistance to stress, and a great deal of hybrid cultivars with good processing quality were derived from sexual hybridization between Thinopyrum species and wheat. An attempt was made to discover its unique excellent HMW-GS gene(s) and to use these genes in wheat quality improvement. The objectives of this study are to analyze the compositions of HMW-GS in311Th. intermedium-derived lines. The results are as follows:1. The composition and allelic variation of HMW glutenin subunits were analysed by using SDS-PAGE method in a total of311wheat-alien introgression lines from Th. intermedium. Three allelic variants were detected for Glu-Al. For the Glu-Bl locus, eight of eleven alleles detected have been found, and the high-quality scored subunits,7+8,14+15and17+18,13+16that were few reported previously in Chinese wheat, had a frequency of62.1%; while five of nine alleles for the Glu-Dl were also detected, the good subunit5+10being38.9%. Considering the three loci, thirty two combinations were found among all the evaluated lines, and of them, the high-quality scored ones accounted for52.73%. This wide polymorphism could be useful to enhance the genetic variability available for improving the quality of bread wheat.2. The HMW-GS with high quality tested by SDS-PAGE technique in wheat-Th. intermedium introgression lines were further identified using specific PCR marker for80known subunits. The results demonstrated that, for Glu-Al locus, specific primers UMN19was amplified344bp bands in part of the tested materials, indicating that these materials had Ax2*subunit; the remaining were amplified a362bp band, indicating these materials contained AX1or Ax-Null subunit; and their frequency of the quality subunits Ax2*is31.2%. For Glu-D1locus, specific primers UMN25was amplified the281bp bands in some lines, which showed that they had Dx5subunit; some material was amplified299bp bands, suggesting that these materials contained Dx2subunit; and the frequency of high-quality subunit Dx5is34.3%; some was amplified397bp bands for pecific primer UMN26, indicating that Dy10subunit present in these materials; others was amplified415bp bands, indicating that they contained Dy12subunit; and the frequency of the quality subunit Dy10is32.7%. For Glu-B1locus, specific primers cauBx642and cauBx752were amplified642bp and752bp bands respectively in certain materials, indicating that they had Bxl4subunit, the appeared frequency of Bxl4is20%; some materials were also amplified the534bp and337bp bands respectively, indicating that they had Bx17subunit, the appeared frequency of Bx17subunit is34%, being much higher than that of Chinese wheat cultivars; the specific primers ZSBy9aF1/R3was amplified662bp bands in some materials, showing that By9subunit was present in these materials, and its frequency is6.2%. In the all tested materials, the appeared frequency having high quality subunits5+10is31%; the frequency of subunit2+12is37%, and discovered new subunits5+12and2+10, accounting for2.5%and3.75%; which were largely consistent with those of SDS-PAGE analysis. The identified HMW-GS alleles with good quality, along with their molecular markers, could be used in marker-assisted selection for high quality subunit and compositions, thereby enhancing the selection efficiency and speeding up the breeding process.