Allelic variation at Glu-1 loci and its association with grain quality of wheat grown in an irrigated hot environment
The high molecular weight glutenin subunits (HMW-GS) are important determinants of wheat flour quality. The HMW-GS patterns of the major released wheat cultivars in Sudan, in addition to some advanced lines, were analyzed using SDS-PAGE. The associations of the HMW-GS quality scores (Glu-1 QS) with the flour protein content (PC), insoluble protein content (IPC), sodium dodecyl sulfate sedimentation (SDSS) test and some mixograph attributes measured using flours of 16 wheat genotypes grown in a hot irrigated environment were also studied. A total of 15 different HMW-glutenin individual subunits were detected. Particularly, three subunits (null, 1 and 2*) were identified at Glu-A1, eight subunits at Glu-B1 that fall into six subunit combinations (7, 7+8, 7+9, 7+151, 13+16 and 17+18) and four subunits at the Glu-D1 locus that fall into two combinations (2+12 and 5+10). Some cultivars were heterogeneous in their HMW-GS composition such as El Nielain, Sasaraib and Nesser. The Glu-1 QS significantly correlated with PC, IPC, SDSS and mixograph curve width 2 min past peak. However, no significant associations were found between Glu-1 QS and other mixograph parameters such as mixograph peak height, mixograph peak time and mixograph descending slope 2 min past peak. The results show that subunit combination of 5+10 that has major effect on dough strength was lacking in all cultivars released before 1990, while the frequency of this subunit combination was high in the tested advanced lines. The results obtained in this study could be useful in breeding programs to improve the end-use quality in bread wheat. HMW-GS patterns could also serve as complementary markers in cultivar identification, purification and improvement.
Key works: Wheat, high molecular weight glutenin subunits, SDS-PAGE, allelic variation, quality scores, hot environment.