Abstract
BackgroundFlax (Linum usitatissimum L.) is grown for fiber and seed in many countries. Flax cultivars differ in the oil composition and, depending on the ratio of fatty acids, are used in pharmaceutical, food, or paint industries. It is known that genes of SAD (stearoyl-ACP desaturase) and FAD (fatty acid desaturase) families play a key role in the synthesis of fatty acids, and some alleles of these genes are associated with a certain composition of flax oil. However, data on genetic polymorphism of these genes are still insufficient.ResultsOn the basis of the collection of the Institute for Flax (Torzhok, Russia), we formed a representative set of 84 cultivars and lines reflecting the diversity of fatty acid composition of flax oil. An approach for the determination of full-length sequences of SAD1, SAD2, FAD2A, FAD2B, FAD3A, and FAD3B genes using the Illumina platform was developed and deep sequencing of the 6 genes in 84 flax samples was performed on MiSeq. The obtained high coverage (about 400x on average) enabled accurate assessment of polymorphisms in SAD1, SAD2, FAD2A, FAD2B, FAD3A, and FAD3B genes and evaluation of cultivar/line heterogeneity. The highest level of genetic diversity was observed for FAD3A and FAD3B genes – 91 and 62 polymorphisms respectively. Correlation analysis revealed associations between particular variants in SAD and FAD genes and predominantly those fatty acids whose conversion they catalyze: SAD – stearic and oleic acids, FAD2 – oleic and linoleic acids, FAD3 – linoleic and linolenic acids. All except one low-linolenic flax cultivars/lines contained both the substitution of tryptophan to stop codon in the FAD3A gene and histidine to tyrosine substitution in the FAD3B gene, while samples with only one of these polymorphisms had medium content of linolenic acid and cultivars/lines without them were high-linolenic.ConclusionsGenetic polymorphism of SAD and FAD genes was evaluated in the collection of flax cultivars and lines with diverse oil composition, and associations between particular polymorphisms and the ratio of fatty acids were revealed. The achieved results are the basis for the development of marker-assisted selection and DNA-based certification of flax cultivars.
Highlights
Flax (Linum usitatissimum L.) is grown for fiber and seed in many countries
The detailed results are represented in Additional files 2, 3, 4, and 5 in the form of variant tables and heatmaps
We revealed a large number of polymorphisms in FAD3A and FAD3B genes and found among them a significant number of those associated with the fatty acid composition (9 for FAD3A and 11 for FAD3B), the further analysis of the obtained data showed that only three variants play a key role in the determination of the ratio of linoleic and linolenic acids in our sample set – Single nucleotide polymorphism (SNP) in sites CP027631.1:16092348, CP027631.1: 16090340, and CP027622.1:1035655 resulting in stop codons in the FAD3A gene and histidine to tyrosine substitution in FAD3B
Summary
Flax cultivars differ in the oil composition and, depending on the ratio of fatty acids, are used in pharmaceutical, food, or paint industries. Flax seed is one of the leading sources of healthy ω-3 fatty acid (linolenic, LIN, C18:3), whose content in regular flax is about 50–60%. Flax cultivars differ in the fatty acid composition of oil: solin flax, unlike traditional, has a very low LIN content (less than 5%), rich in LIO, and is characterized by long-term storage that is important for food industry [1,2,3,4]. For optimal health and disease prevention, in the diet, the ω-6/ω-3 ratio is required to be 1–3/1; and the content of oxidative stable monounsaturated OLE is important for the production of stable and healthy oils and other products [3, 6,7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
