Genetic variation of wheat glutenin subunits between landraces and varieties and their contributions to wheat quality improvement in China

Glutenin, one of major factors effecting bread-making quality, is comprised of a mixture of polymers, viz. high-molecular-weight glutenin subunits (HMW-GSs) and low-molecular-weight glutenin subunits (LMW-GSs). Understanding variation among these glutenin subunits can help breeders determine allelic effects on specific quality traits and to use them as genetic markers. The HMW-GS and LMW-GS compositions of 390 landraces and 225 released varieties were analyzed by SDS–PAGE, and some quality traits, including Zeleny sedimentation volume, dough development time, stability time and strengths, were evaluated. The results indicated that 17 and 13 HMW-GSs were present in landraces and released varieties, respectively. For LMW-GS ( Glu-A3 and Glu-B3 loci), 12 alleles were found in both landraces and released varieties. Total allelic richness at glutenin loci in landraces was higher, but the genetic dispersion index was lower than in released varieties. Two new subunit combinations 6 + 16 and 7 + 22, and some rare subunits 6 + 9*, 23 + 22, 6* + 8, 7 and 8, were identified in landraces and released varieties. The Glu-D1 and Glu-B3 loci had significantly positive effects. Based on the comparison of the effect of each subunit on quality, it was concluded that subunits 1 at Glu-A1 , 13 + 16, 17 + 18 and 6 + 16 at Glu-B1 , 5 + 10 at Glu-D1 , Glu-A3b at Glu-A3 and Glu-B3d at Glu-B3 contributed larger positive effects on bread-making quality than alternative alleles. From this study, genetic materials with strong gluten and good quality were identified in landraces that did not carry the 1BL.1RS translocation.