Novel High Molecular Weight Glutenin Subunits at the Glu-D1 Locus in Wheat Landraces from the Xinjiang District of China and Relationship with Winter Habit

Allelic variation of high molecular weight glutenin subunits (HMW-GS) encoded by Glu-A1, Glu-B1 and Glu-D1 in wheat landraces originating from the Xinjiang Uygur Autonomous District (Xinjiang District) of China was investigated by SDS-PAGE and the relationship between the variation and the winter habit was examined. The most frequent allele at the Glu-A1 locus was Glu-A1c (null allele: 75.5%), followed by Glu-A1b encoding subunit 2* (22.3%). These two alleles were distinctive at Glu-A1 in the landraces of both spring and winter cultivars. No difference in allele frequency was found between the spring and the winter wheat cultivars. At the Glu-B1 locus, the most frequent allele was Glu-B1b (90.8%) encoding subunits 7 + 8, the allele frequency of which was almost the same between the spring and the winter wheat cultivars. Glu-D1a (72.0%) encoding subunits 2 + 12 was a major allele at the Glu-D1 locus among the landraces. Although no cultivar with Glu-d1f encoding subunits 2.2 + 12 was found, the novel subunit pair 2.6 + 12 (24.5%) was observed only in the winter wheat cultivars. Subunit 2.6 was slightly less mobile than subunit 2.2. The major Glu-D1 allele was Glu-D1a (94.5%) among the spring wheat cultivars and this allele characterized the spring wheat cultivars in the Xinjiang District. Both the subunit pair 2.6 + 12 encoded by the Glu-D1bp(t) allele (58.5%) and the subunit pair 2 + 12 encoded by the Glu-D1a allele (40.7%) predominated among the winter wheat cultivars. The large difference in allelic variation at the Glu-D1 locus suggested that the origin of the spring wheat cultivars was different from that of the winter wheat cultivars. The absence of landrace with Glu-D1f suggested that Xinjiang wheat was not related to Japanese wheat.