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CDC Dorado is a yellow seed coat oilseed flax (Linum usitatissimum L.) registered in 2017 by the Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada. This cultivar has a 7% higher yield than AC Nugget in the Black soil zone of the prairies coupled with a earlier maturity than Flanders across 10 site-years in western Canada. It has a medium (45.2%) oil content, high iodine value (204.2), an α-linolenic acid content of 64%, and a 1000-seed weight of 6.0 g. It is immune to flax rust caused by Melampsora lini (Ehrenb.) Thüm. and is moderately resistant to wilt and powdery mildew caused by Fusarium oxysporum Schltdl. f. sp. lini (Bolley) W.C. Snyder & H.N. Hansen and Oidium lini, respectively.

CDC Melyn is a yellow seed coat oilseed flax (Linum usitatissimum L.), registered in 2016 by the Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada. This cultivar has a yield (106%) comparable to the cultivar AC Nugget (the yield standard for yellow seed coat oilseed flax) and a maturity rating equal to Flanders. It has a medium (46.6%) oil content, iodine value (199.4), alpha-linolenic acid content (61%), and a 1000-seed weight of 5.0 g. It is immune to flax rust caused by Melampsora lini (Ehrenb.) Thüm. and moderately resistant to wilt and powdery mildew caused by Fusarium oxysporum Schltdl. f. sp. lini (Bolley) W.C. Snyder & H.N. Hansen and Oidium lini, respectively.

CDC Plava oilseed flax (Linum usitatissimum L.), registered in 2015 by the Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada, is targeted to the shorter growing season and the Dark Brown, Black, Grey, and Dark Grey soil zones of the northern prairies. This cultivar has a high seed yield (106%) compared with cultivar CDC Bethune and a medium maturity rating equal to Prairie Thunder. It has medium oil content (47.0%), α-linolenic acid content (57.8%), seed size (6.1 g 1000-seed weight), and good lodging resistance. It is resistant to North American races of rust caused by Melampsora lini (Ehrenb.) Thüm. and moderately resistant to wilt caused by Fusarium oxysporum Schltdl. f. sp. lini (Bolley) W.C. Snyder & H.N. Hansen.

CDC Buryu, a late maturing oilseed flax (Linum usitatissimum L.), was registered in 2016 by the Crop Development Centre, University of Saskatchewan, Saskatoon, SK, Canada. This cultivar had a yield (106%) comparable to CDC Bethune and a maturity rating equal to Flanders in all soil zones of the northern prairies. The yield advantage over CDC Bethune was greater (>8%) in the Brown soil and Black soil zones of the northern prairies. It had medium oil content, oil quality, and seed size and good lodging resistance. It is immune to North American rust (race 371) caused by Melampsora lini (Ehrenb.) Thüm. and moderately resistant to wilt caused by Fusarium oxysporum Schltdl. f. sp. lini (Bolley) W.C. Snyder & H.N. Hansen and powdery mildew caused by Oidium lini.

The flowers of flax (linseed) are blue-hued, ephemeral and self-pollinating, and the seeds are typically brown. A century-old interest in natural yellow seed variants and a historical model point to recessive alleles in B1, D and G loci being responsible, but the functional aspects had remained unknown. Here, we characterized the “D” locus by quantitative trait loci (QTL) mapping and identified a FLAVONOID 3′5′ HYDROXYLASE (F3′5′H) gene therein. It does not belong to the F3′5′H clade, but resembles biochemically characterized F3′Hs (flavonoid 3′ hydroxylase) but without F3′H activity. The genome lacks other F3′H or F3′H-like genes. The apparent neo-functionalization from F3′H is associated with a Thr498 → Ser498 substitution in a substrate recognition site (SRS). The yellow seed and white flower phenotypes of the classical d mutation was found to be due to one nucleotide deletion that would truncate the deduced product and remove three of the six potential SRS, negatively impacting delphinidin synthesis. Delphinidin is sporadic in angiosperms, and flax has no known pollination syndrome(s) with functional pollinator group(s) that are attracted to blue flowers, raising questions on the acquisition of F3′5′H. The appearance of d allele is suggestive of the beginning of the loss of F3′5′H in this species., Erratum published online 12 March 2018 DOI: 10.1038/s41598-018-22651-9

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Flax secoisolariciresinol (SECO) diglucoside (SDG) lignan is an emerging natural product purported to prevent chronic diseases in humans. SECO, the aglycone form of SDG, has shown higher intestinal cell absorption but it is not accumulated naturally in planta. Recently, we have identified and characterized a UDP-glucosyltransferase gene, UGT74S1, that glucosylates SECO into its monoglucoside (SMG) and SDG forms when expressed in yeast. However, whether this gene is unique in controlling SECO glucosylation into SDG in planta is unclear. Here, we report on the use of UGT74S1 in reverse and forward genetics to characterize an ethyl methane sulfonate (EMS) mutagenized flax population from cultivar CDC Bethune and consisting of 1996 M2 families. EMS mutagenesis generated 73 SNP variants causing 79 mutational events in the UGT74S1 exonic regions of 93 M2 families. The mutation frequency in the exonic regions was determined to be one per 28 Kb. Of these mutations, 13 homozygous missense mutations and two homozygous nonsense mutations were observed and all were transmitted into the M3 and M4 generations. Forward genetics screening of the population showed homozygous nonsense mutants completely lacking SDG biosynthesis while the production of SMG was observed only in a subset of the M4 lines. Heterozygous or homozygous M4 missense mutants displayed a wide range of SDG levels, some being greater than those of CDC Bethune. No additional deleterious mutations were detected in these mutant lines using a panel of 10 other genes potentially involved in the lignan biosynthesis. This study provides further evidence that UGT74S1 is unique in controlling SDG formation from SECO and this is the first report of non-transgenic flax germplasm with simultaneous knockout of SDG and presence of SMG in planta.