Abstract：The seed oil of flax (Linum usitatissimum L.)is notable for its high level of polyunsaturated fatty acids including linolenic acid,which could be oxidized by lipoxygenase,which result in oxidative acidity of oils.Therefore, stability and offflavors are vital characteristics that determine the quality of flax oil. Lipoxygenases (LOXs)are a class of nonheme iron containing dioxygenases which catalyze the hydroperoxidation of polyunsaturated fatty acids such as linoleic and linolenic acids. Experiments were conducted in order to elucidate the role of LOXs during seed development and in relation to seed oil quality. The full length cDNA of LuLOX1 was cloned based on flax whole genome DNA sequence database.The expression of LuLOX1 was determined by RTPCR and the catalytic activity of LuLOX1 was determined by spectrophotometer. Results have shown that the CDNA of LuLOX1gene was 2 607 bp, encoding a protein of 868 amino acids. The molecular weight and isoelectric point of LuLOX1 were 97.87 kD and 6.36, respectively.RTPCR carried out with RNAs extracted from seeds at different development stages showed that LOX is mainly expressed at early developmental stages.The results were consistent with those of LOX activity assays. The patterns of LuLOX1 expression were consistent with LuLOX1 activities.This indicated that LuLOX1 might be involved in regulation of fatty acid oxidation during seed development. These results laid the foundation for further study on the function of LuLOX1that may play an important role in enhancement of the quality of flaxseed oil through lipoxygenase.
