Mapping genomic regions controlling agronomic traits in spring wheat under conventional and organic managements

Identification of quantitative trait loci (QTL) associated with important traits is one of the first steps towards deploying marker-assisted selection, but the lack of stability and consistency in identifying QTL across environments and populations remains a limitation. We conducted this study to identify QTL associated with agronomic traits in wheat (Triticum aestivum L.) across management-specific environments. A total of 204 wheat lines derived from the 'Peace' x 'Carberry' cross were evaluated in 2016 and 2017 under conventional and organic managements in Edmonton, Canada, and genotyped with diversity arrays technology markers. Using the least-squares means for each management system, 53 QTL were identified for nine agronomic traits, 14 of which were consistently identified in both managements. The largest QTL we identified was associated with plant height (QPht.dms-4B), which might be the plant height-reducing gene Rht-B1b from 'Carberry'. It explained 54 and 49% of the phenotypic variation in conventional and organic management, respectively. The second largest QTL was associated with gluten strength (QSds.dms-1A) in both managements. We identified consistent QTL across both organic and conventional managements, even though they were generally minor-effect QTL. Twelve organic management-specific QTL were found for grain yield, days to heading and maturity, plant height, test weight, and thousand-kernel weight, but most explained relatively low amount of phenotypic variation. The QTL identified across managements, especially the gluten strength QTL (QSds.dms-1A), may serve as useful markers in selection. The QSds.dms-1A region needs to be investigated further to confirm whether it is the Gli-1 storage protein gene.