*4.1. Plant Materials*

Three bi-parental mapping populations of different genetic backgrounds served as genotype panel for the association study. The first population (BM) consisted of 243 F6-derived RILs generated by single seed descent from a cross between CDC Bethune and Macbeth. Its two parents are Canadian high-yielding conventional linseed cultivars with 55–57% LIN [65,66]. The second population (EV) contained 90 F6-derived RILs from a cross between E1747, an ethyl methanesulfonate (EMS)-induced low LIN breeding line [67], and Viking, a French fiber flax cultivar with ~55% LIN that was grown extensively in the 2000's but deregistered in 2012. The third population (SU) is an F1-derived DH population of 78 lines obtained from a cross between the breeding line SP2047, from which a yellow-seeded SolinTM 2047 with only 2–3% LIN has been derived, and breeding line UGG5-5, which is a high LIN line with 63–66% LIN [7,55]. BM was designed to study yield-related traits while EV and SU were intended for QTL identification for fatty acid composition and fiber traits.
