Evaluation of Grain Quality Traits, Glutenin Subunits and Their Relationship in Durum Wheat

To study grain quality traits and their relationships with high molecular weight (HMW) and low moleculor weight (LMW) glutenin subunits, 104 durum wheat genotypes were used. Six grain quality characteristics comprising wet and dry gluten content, test weight, grain hardiness, protein content and SDS sedimentation volume were studied. HMW and LMW glutenin subunits were evaluated using SDS-polyacrylamid gel electrophoresis (SDS-PAGE) in 33 genotypes. Statistical analysis including correlation coefficients, factor analysis, cluster analysis of genotypes based on qualitative traits, analysis of variance in qualitative traits based on HMW, LMW, and combination of subunits as well as all of subunits, and canonical correlation analysis between glutenin subunits and qualitative traits were used. Factor analysis of the genotypes detected 2 factors, which explained 65 percent of the total variation among the data. These were named quantitative protein and qualitative protein. Based on cluster analysis, the genotypes were classified into four clusters. The genotypes in groups 2 and 4 were beneficial in terms of protein quantity and quality. In evaluating glutenin subunits, 7 HMW subunits and 2 LMW subunits were detected. Subunit null of Glu-Al was observed. Subunits 7+8, 6+8, 13+16 and 20 at Glu-Bl were observed however, neither of them had significant differences in qualitative traits, but 6+8 and 7+8 had a higher SDS sedimentation rate than 20. LMW-1 and LMW-2 had significant differences in protein content and SDS sedimentation LMW-1 had higher protein content whereas LMW-2 had higher SDS sedimentation. Combibation of subunit LMW-1 / HMW 7+8 had the highest protein content and LMW-2/HMW 7+8 had the highest SDS sedimentation. Results of canonical correlation showed that presence of LMW-2 and HMW 7+8, and absence of LMW-1 and HMW 20 in durum wheats caused an increase in SDS sedimentation and a reduction in protein and gluten content.