Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
Peoples' Friendship University of Russia (RUDN University), Moscow, Russia.
BMC Plant Biol. 2020 Oct 14;20(Suppl 1):301. doi: 10.1186/s12870-020-02499-w.
Flax (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.
On 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.
Genetic 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.
亚麻（Linum usitatissimum L.）在许多国家被种植用于纤维和种子。亚麻品种在油组成上存在差异，并且根据脂肪酸的比例，用于制药、食品或油漆行业。已知 SAD（硬脂酰-ACP 去饱和酶）和 FAD（脂肪酸去饱和酶）家族的基因在脂肪酸合成中起关键作用，并且这些基因的一些等位基因与亚麻油的特定组成有关。然而，关于这些基因的遗传多态性的数据仍然不足。
基于托罗日克亚麻研究所（Torzhok，俄罗斯）的收藏，我们形成了一个代表 84 个品种和系的集合，反映了亚麻油脂肪酸组成的多样性。开发了一种使用 Illumina 平台确定 SAD1、SAD2、FAD2A、FAD2B、FAD3A 和 FAD3B 基因全长序列的方法，并在 MiSeq 上对 84 个亚麻样本中的 6 个基因进行了深度测序。获得的高覆盖率（平均约 400x）能够准确评估 SAD1、SAD2、FAD2A、FAD2B、FAD3A 和 FAD3B 基因中的多态性，并评估品种/系的异质性。在 FAD3A 和 FAD3B 基因中观察到最高水平的遗传多样性 - 分别为 91 和 62 个多态性。相关性分析显示 SAD 和 FAD 基因中的特定变体与它们催化的主要脂肪酸之间存在关联：SAD-硬脂酸和油酸，FAD2-油酸和亚油酸，FAD3-亚油酸和亚麻酸。除一个低亚麻酸品种/系外，所有品种/系均含有 FAD3A 基因中色氨酸到终止密码子的取代和 FAD3B 基因中组氨酸到酪氨酸的取代，而只有其中一种多态性的样本中亚麻酸含量中等，而没有这些多态性的品种/系则是高亚麻酸。
评估了具有不同油组成的亚麻品种和系中 SAD 和 FAD 基因的遗传多态性，并揭示了特定多态性与脂肪酸比例之间的关联。所获得的结果是开发标记辅助选择和基于 DNA 的亚麻品种认证的基础。
