The genetic structure of flax illustrates environmental and anthropogenic selections that gave rise to its eco-geographical adaptation

Citation

Sertse, D., You, F.M., Ravichandran, S., Cloutier, S. (2019). The genetic structure of flax illustrates environmental and anthropogenic selections that gave rise to its eco-geographical adaptation. Molecular Phylogenetics and Evolution, [online] 137 22-32. http://dx.doi.org/10.1016/j.ympev.2019.04.010

Plain language summary

Flax, one of the eight founder crops of agriculture, has been cultivated for its oil and/or fiber for millennia. Understanding genetic divergence and geographic origins of germplasm in line with their cultivation history and ecological adaptation are essential for conservation and breeding. Here we sequenced 383 flax accessions from a core collection representing 37 flax growing countries, identified more than 51,000 single nucleotide polymorphic sites and used this data to perform a genome-wide analysis of flax diversity. The population structure analysis performed revealed 12 populations representing four major groups: Temperate, South Asian, Abyssinian and Mediterranean. The vast majority (87%) of the accessions belonged to the Temperate group that comprised eight populations. We noticed that genetic variation between fiber and oil types was less pronounced than variation within each type. Eco-geographic and anthropogenic factors played a significant role in the partitioning the genetic variation. Environmental factors such as day length were important in population assignment. The South Asian, Mediterranean and Abyssinian populations were characterized by germplasm of unique genetic make-up that were rare in the overall collection but that hinted at the long history of the crop in these regions. The addition of genotypes from these three regions would enrich the core collection by capturing a wider genetic breadth for breeding and conservation.

Abstract

Flax, one of the eight founder crops of agriculture, has been cultivated for its oil and/or fiber for millennia. Understanding genetic divergence and geographic origins of germplasm in line with their cultivation history and ecological adaptation are essential for conservation and breeding. Here we performed a genome-wide assessment based on more than 51,000 single nucleotide polymorphic sites defining 383 flax accessions from a core collection representing 37 flax growing countries. Population structure analysis resulted in a total of 12 populations that were pooled into four major groups: Temperate, South Asian, Abyssinian and Mediterranean. The vast majority (n = 335)belonged to the Temperate group that comprised eight populations including one dominated by fiber flax. Genetic variation between fiber and oil morphotypes was less pronounced than variation within morphotypes. The genetic variation among groups and populations was attributed in part to eco-geographic and anthropogenic factors. Genetic signatures indicated loci under strong selection by environmental factors such as day length. A high concentration of private haplotypes were observed in the South Asian, Mediterranean and Abyssinian populations despite their low genotype representation, hinting at the long history of the crop in these regions. The addition of genotypes from these three regions would enrich the core collection by capturing a wider genetic breadth for breeding and conservation.

Publication date

2019-08-01