Fungi, like plants, are capable of producing the 18-carbon polyunsaturated fatty acids linoleic acid and α-linolenic acid. These fatty acids are synthesized by catalytic reactions of Δ12 and ω3 fatty acid desaturases. This paper describes the first cloning and functional characterization of a yeast ω3 fatty acid desaturase gene. The deduced protein encoded by the Saccharomyces kluyveri FAD3 gene (Sk-FAD3) consists of 419 amino acids, and shows 30–60 % identity with Δ12 fatty acid desaturases of several eukaryotic organisms and 29–31 % identity with ω3 fatty acid desaturases of animals and plants. During Sk-FAD3 expression in Saccharomyces cerevisiae, α-linolenic acid accumulated only when linoleic acid was added to the culture medium. The disruption of Sk-FAD3 led to the disappearance of α-linolenic acid in S. kluyveri. These findings suggest that Sk-FAD3 is the only ω3 fatty acid desaturase gene in this yeast. Furthermore, transcriptional expression of Sk-FAD3 appears to be regulated by low-temperature stress in a manner different from the other fatty acid desaturase genes in S. kluyveri.
The effects of foliar application of melatonin on some physiological and biochemical characteristics and expression of fatty acid desaturase gene in pistachio seedlings (Pistacia vera L.) under freezing stress
