Genetic Structure of the Perennial Flax Trifecta: Linum austriacum, L. lewisii, L. perenne

Background/Objectives. Annual flaxseed (Linum usitatissimum) is the most cultivated Linum species. Perennial species (Linum austriacum, Linum lewisii, Linum perenne) show potential as alternative oilseed and fiber sources. It is critical to determine genetic variation in any collection to understand relationships and utilization within a breeding program. The research objectives were to analyze the genetic structure of the trifecta perennial flax using single-nucleotide polymorphic (SNP) markers for species differentiation and to discover potential Centers of Origin and/or diversity. Methods. We tested 70 USDA-GRIN-global wild populations (19 L. austriacum, 32 L. lewisii, 19 L. perenne; N = 850 seedling genotypes) to generate 9804 DArTseqLD SNPs (Group 1). Results. After filtering, within L. austriacum, 1199 SNPs (261 genotypes; Group 2) remained; in L. lewisii, there were 90 unique SNPs (273 genotypes; Group 3); in L. perenne, there were 2716 SNPs (309 genotypes; Group 4). Four genetic clusters were detected using STRUCTURE, consistent with principal coordinate analysis and SplitsTrees. Clear distinctions within and among each perennial species’ populations were found, separating into two distinct pure taxon groupings, along with peripheral populations or outliers. Both L. austriacum and L. lewisii potentially had two putative Centers of Origin, although L. perenne had one. Conclusions. The occurrence of sympatric Linum species in the wild could explain the occurrence of peripheral population groups within each taxon, although other explanations are also possible. This may be consistent with the potential for genetic exchange between the perennial species and the greater genetic variability available. Future research will evaluate additional Linum to further delineate the genetic structure and variation within the genus Linum.