In order to find the relationships between high molecular weight glutenin subunits and breadmaking quality of wheat, 280 advanced breeding lines of wheat were studied. We used SDS-PAGE procedure for fragmenting the glutenin and a total of 19 subunits were found of which 5+12 , 5*+12 subunits in GLU-DI and 17+9 subunits in GLU-Bi haven’t been reported hefore.Breadmaking quality of the lines was evaluated indirectly by f’arinograph test, protein %, loaf volume, hardness of seed, Zeleny and SDS-sedimentation test. Using one-way analysis of variance and regression analysis, we found that I and 2’ subunits from Glu-Al, 17+18, 13+16 and 7+8 subunits from Glu-Bi loci were more valuable than the other subunits for breadmaking quality. Subunits 5+10 had significant favorable effect on bread-making quality than their allelic counterparts 2+ 12. The principal component analysis showed that the first two principal components explained 80% of the variation for the breadmaking quality. Coefficients of correlation between the first principal component and percent of protein, Zeleny, loaf volume, hardness of the seed and the correlation of the second principal component with SDS- sedimentation were 0.84, 0.90, 0.88, 0.66, and 0.99, respectively. The principal component analysis showed that the four principal components explained 81% of the variation k)r the HMW glutenin subunits. The allelic frequency in each country (origin of the lines) was used to estimate the dissimilarity coefficient by Euclidean distance method and also to determin the Nei’s genetic identity index. Countries were clustered in 3 groups. Nei’s genetic diversity for the three loci worked out for the countries. This study showed that coefficient of correlation between quality scoring system and diversity was negative, which means that the intensity of selection pressure towards good allels over a long period of time had been the main factor. Artificial selection for the good quality during the revolutionary period had been the main factor to reduce genetic diversity.
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