Functional characterization of two microsomal fatty acid desaturases from Jatropha curcas L.

Linoleic acid (LA, C18:2) and α-linolenic acid (ALA, C18:3) are polyunsaturated fatty acids (PUFAs) and major storage compounds in plant seed oils. Microsomal ω-6 and ω-3 fatty acid (FA) desaturases catalyze the synthesis of seed oil LA and ALA, respectively. Jatropha curcas L. seed oils contain large proportions of LA, but very little ALA. In this study, two microsomal desaturase genes, named JcFAD2 and JcFAD3, were isolated from J. curcas. Both deduced amino acid sequences possessed eight histidines shown to be essential for desaturases activity, and contained motif in the C-terminal for endoplasmic reticulum localization. Heterologous expression in Saccharomyces cerevisiae and Arabidopsis thaliana confirmed that the isolated JcFAD2 and JcFAD3 proteins could catalyze LA and ALA synthesis, respectively. The results indicate that JcFAD2 and JcFAD3 are functional in controlling PUFA contents of seed oils and could be exploited in the genetic engineering of J. curcas, and potentially other plants.