Genetic diversity for high- and low-molecular weight glutenin subunits in local and commercial bread wheat cultivars released since 1951 in Iran: I- Irrigated

Allelic variations at the Glu-1 and Glu-3 loci play an important role in determining dough visco-elastic properties and bread making quality. Fifty-nine bread wheat cultivars released in Iran since 1951 from four different agroclimate zones, were examined for their high (HMW-GS) and low-molecular-weight glutenin subunit (LMW-GS) composition, controlled at the Glu-1 and Glu-3 loci, respectively. In addition, the presence of the 1B.1R translocation was investigated. Three, eight, and four allelic variations were present at Glu-A1, Glu-B1, and Glu-D1 loci, respectively. Subunits 2*, 7+8, 7+9, and 2+12 are the dominant HMW-GS, at Glu-A1, Glu-B1, and Glu-D1, with frequencies of 45.8, 39, 25.4, and 59.3%, respectively. Five, eight and four allelic variations were present at the Glu- A3, Glu-B3 and Glu-D3 loci, with Glu-A3c, Glu-B3b and Glu-D3b LMW-GS dominating, with frequencies of 52.5, 39 and 59.3%, respectively. The frequencies of allelic variation at Glu-1 and Glu-3 differ greatly in different regions. Among the 59 cultivars/varieties examined in this study, four genotypes were local varieties (6.8%), 27 (45.8%) bred in the national breeding program and 28 (47.4%) originated from international nurseries. The average quality scores based on HMW-GS for local varieties, genotypes from the national breeding program and international nurseries were 5.5, 7.6 and 7.7 respectively. It was concluded that integration of desirable subunits at Glu-1 such as 1, 7+8, 5+10, must be used as the core focus of the breeding program, which could lead to the improvement of gluten quality in Iranian bread wheat cultivars.