Geographical Distribution of High-Molecular-Weight Glutenin Subunits and Characterization of a New High-Molecular-Weight Glutenin Subu nit of Winter Wheat Landraces(Triticum aestivum L.)in the Xinjiang Uygur Autonomous District of China

[Objective and Method]We studied the regional distribution of high - molecular - weight glutenin subunit(HMW - GS) alleles(Glu - 1 ) in common wheat landraces with winter habit in the northern,the eastern and the southern regions in the Xinjiang - Uygur Autonomous District(Xinjiang) in China.[Result]The investigation of regional differences in allele frequencies of the three loci affecting HMW - GS revealed that regional differences were not statistically significant for the Glu - B1 locus,but significant for the Glu -A1 and Glu - D1 loci.As for the Glu - A1 locus,the allele frequency of Glu -A1c encoding the null subunit was the highest,followed by Glu -A1b encoding the subunit 2* throughout the district,but in the northern region,all cultivars harbored Glu -A1c except only one cultivar with Glu -A1b.At the Glu - B1 locus,most of Xinjiang landraces had Glu - B1b encoding the subunit pair 7 +8.At the Glu -D1 locus,the recently identified allele Glu - D1bp(t) encoding the subunit pair 2.6 + 12 was distributed in higher frequencies in the eastern and the southern regions but less frequent in the northern region.Its frequencies were 17%,91%and 66%in northern,eastern and southern regions,respectively.In the southern region, the majority of landraces had Glu -Dlbp(t) throughout the region.In the northern region,however,the majority(83%) of the allele was Glu -D1a encoding the subunit pair 2 + 12.Regarding to the origin of Glu -D1bp(t),the new allele might appear by a spontaneous mutation and become a major allele by a bottleneck effect caused by the afterward occurring desertification in the southern and the eastern regions,and a few cultivars were thought to be spread to the northern region,but landraces with this allele to be not transferred to East Asia.[Conclusion]Based on the comparison of amino acid sequences deduced from DNA sequence,we found that the subunit 2.6 encoded by Glu -D1bp(t) had very high similarity with the subunit 2.2* encoded by Glu - D1al.