Expression of and Genes in Developing Seeds of Flax Varieties under Different Growth Conditions.

Flax seed is one of the richest plant sources of linolenic acid (LIN) and also contains unsaturated linoleic acid (LIO) and oleic acid (OLE). Stearoyl-ACP desaturases (SADs) and fatty acid desaturases (FADs) play key roles in the synthesis of flax fatty acids (FAs). However, there is no holistic view of which genes from the and families and at which developmental stages have the highest expression levels in flax seeds, as well as the influence of genotype and growth conditions on the expression profiles of these genes. We sequenced flax seed transcriptomes at 3, 7, 14, 21, and 28 days after flowering (DAF) for ten flax varieties with different oil FA compositions grown under three temperature/watering conditions. The expression levels of 25 genes of the , , and families were evaluated. , , , , , , , , and had the highest expression levels, which changed significantly during seed development. These genes probably play a key role in FA synthesis in flax seeds. High temperature and insufficient watering shifted the maximum expression levels of and genes to earlier developmental stages, while the opposite trend was observed for low temperature and excessive watering. Differences in the and expression profiles under different growth conditions may affect the FA composition of linseed oil. Stop codons in the gene, resulting in a reduced LIN content, decreased the level of transcript. The obtained results provide new insights into the synthesis of linseed oil.