THE HMW GLUTENIN SUBUNIT COMPOSITION OF BREAD-WHEAT VARIETIES BRED INPAKISTAN

A total of 50 bread-wheat varieties bred in Pakistan were characterize d for the composition of the high-molecular-weight glutenin subunit (H MW-GS). The glutenin subunits, as revealed by sodium dodecylsulfate-po lyacrylamide-gel electrophoresis (SDS-PAGE) were numbered according to Payne's numbering system and, varieties were accordingly assigned the oretical quality scores. All varieties were found to possess either su bunit 1 or 2 coded by the A genome. Subunits 17+/-18 and 7+9 of the B genome and 5+10 of the D genome were predominantly found in this set of varieties. The frequency of the appearance of Glu-1 alleles in the varieties was different from that seen in other countries, especially in terms of the absence of the 'null' form of the A genome and the pre sence of novel subunits at the Glu-BI and Glu-D1 loci. The composition s of HMW-GS were generally of good quality, with more than 50% of the varieties achieving quality scores of 9-10 with a high (8.6) average s core. The results in this study indicate that wheat varieties bred in Pakistan have a narrow genetic base in terms of HMW glutenin subunits. It appears that the breeders have been selecting wheat genotypes of g lutenin subunits associated with good quality without knowing the actu al composition of these subunits. The database established on the basi s of these results is useful for wheat-improvement programmes aimed at varietal identification and breeding for good quality parameters.