Effect of Sm1 on End-use Quality of Durum Wheat (Triticum turgidum L. var durum)
Genetic resistance to the orange wheat blossom midge (Sitodiplosis mosellana; OWBM) is an important breeding target to prevent yield and quality losses of durum wheat produced in western Canada. To date, only a single characterized midge resistance gene, Sm1, has been identified. Sm1 confers antibiosis resistance to the OWBM. It has been genetically localized to chromosome 2BS of hexaploid wheat (Triticum aestivum L.). Sm1 has been introgressed into locally adapted germplasm. Currently, no Sm1 carrying durum wheat lines are available for commercial production, and no studies have characterized the influence of Sm1 on yield and end-use quality of durum wheat. The main objectives of this study were: 1) To determine the effect of Sm1 on grain yield and end-use quality. 2) To genetically map the Sm1 introgression. For this work, 122 F5:9 recombinant inbred lines (RILs) derived from a cross between the midge susceptible durum wheat cultivar CDC Verona (Sm1 “-”) and resistant experimental line DT780 (Sm1 “+”). Agronomic and end-use quality traits of the mapping population were analyzed. The results from each environment were used for quantitative trait loci (QTL) analysis at Kernen (SK) in 2009 and 2010, and at Indian Head (SK) in 2009. On average, the presence of Sm1 was associated with higher grain yield and yellow pigment content, but lower kernel weight, reduced grain protein content, and weaker gluten properties. However, it was possible to identify RIL lines carrying Sm1 that expressed higher kernel weight, grain protein content, and stronger gluten. A genetic linkage map spanning 58 cM on chromosome 2B near Sm1 was constructed. QTL mapping suggested that the total length of the Sm1 introgression into durum wheat was approximately 11cM. Nearly all traits measured showed QTLs associated with Sm1. For grain protein content, a QTL proximal to Sm1 was identified, suggesting that Sm1 per se may not be contributing to the reduced grain protein observed in the Sm1 carriers of the RIL mapping population. The results presented here suggest that on average, Sm1 is associated with higher grain yield and some reduced end-use quality factors, but that it may be possible to combine Sm1 with high grain yield and end-use quality equivalent to current check cultivars.
Sm1, orange wheat blossom midge ( OWBM), end-use quality, durum wheat
Master of Science (M.Sc.)