FAD(脂肪酸去饱和酶)和SAD(硬脂酰ACP去饱和酶)基因在脂肪酸(FA)的合成和亚麻(LinumusitatissimumL.)中油脂成分的测定中起着关键作用。我们在CDC白求恩品种最广泛使用的亚麻基因组中搜索了FAD和SAD基因,以及三个可用的长读组装的亚麻基因组YY5、3896和Atlant。我们鉴定了15个FAD2、6个FAD3和4个SAD基因。在所有确定的基因中,24个存在于重复的对中。在大多数情况下,一对中的两个基因的差异在于大量的基因特异性SNP(单核苷酸多态性)甚至InDels(插入/缺失),除了FAD2a-1和FAD2a-2,其中只有七个SNP区分这些基因。在CDC白求恩基因组组装中的FAD2a-1,FAD2a-2,FAD3c-1和FAD3d-2序列中检测到错误,但在长读基因组组装中未检测到错误。对不同亚麻器官/组织的可用转录组数据的表达分析显示,FAD2a-1,FAD2a-2,FAD3a,FAD3b,SAD3-1和SAD3-2在胚/种子/胶囊中特异性表达,并可能在亚麻种子中FA的合成中起关键作用。相比之下,FAD2b-1,FAD2b-2,SAD2-1和SAD2-2在所有分析的器官/组织中均高表达,并且可能参与整个亚麻植物的FA合成。FAD2c-2,FAD2d-1,FAD3c-1,FAD3c-2,FAD3c-2,FAD3d-1,FAD3d-2,SAD3-1和SAD3-2在胁迫条件下表现出差异表达-尖孢镰刀菌感染和干旱。获得的结果对于研究脂肪酸合成的分子机制至关重要。FAD和SAD编辑,以及标记辅助和基因组选择,用于育种具有确定的油脂脂肪酸组成的亚麻品种。
FAD (fatty acid desaturase) and SAD (stearoyl-ACP desaturase) genes play key roles in the synthesis of fatty acids (FA) and determination of oil composition in flax (Linum usitatissimum L.). We searched for FAD and SAD genes in the most widely used flax genome of the variety CDC Bethune and three available long-read assembled flax genomes-YY5, 3896, and Atlant. We identified fifteen FAD2, six FAD3, and four SAD genes. Of all the identified genes, 24 were present in duplicated pairs. In most cases, two genes from a pair differed by a significant number of gene-specific SNPs (single nucleotide polymorphisms) or even InDels (insertions/deletions), except for FAD2a-1 and FAD2a-2, where only seven SNPs distinguished these genes. Errors were detected in the FAD2a-1, FAD2a-2, FAD3c-1, and FAD3d-2 sequences in the CDC Bethune genome assembly but not in the long-read genome assemblies. Expression analysis of the available transcriptomic data for different flax organs/tissues revealed that FAD2a-1, FAD2a-2, FAD3a, FAD3b, SAD3-1, and SAD3-2 were specifically expressed in embryos/seeds/capsules and could play a crucial role in the synthesis of FA in flax seeds. In contrast, FAD2b-1, FAD2b-2, SAD2-1, and SAD2-2 were highly expressed in all analyzed organs/tissues and could be involved in FA synthesis in whole flax plants. FAD2c-2, FAD2d-1, FAD3c-1, FAD3c-2, FAD3d-1, FAD3d-2, SAD3-1, and SAD3-2 showed differential expression under stress conditions-Fusarium oxysporum infection and drought. The obtained results are essential for research on molecular mechanisms of fatty acid synthesis, FAD and SAD editing, and marker-assisted and genomic selection for breeding flax varieties with a determined fatty acid composition of oil.