1.14.19.B9 gene FADX, DNA and amino acid sequence determination and analysis, phylogenetic analysis and tree, quantitative real-time PCR enzyme expression analysis, recombinant expression in Saccharomyces cerevisiae strains ole1 and INVSc1 in microsomes. Santalaceae FADX expressed in yeast has no detectable DELTA12 desaturase activity either acting on native fatty acids or when supplied with exogenous substrates but instead shows cis-DELTA13 desaturation activity on stearolic acid 1.14.19.B9 gene FADX-1A, DNA and amino acid sequence determination and analysis, phylogenetic analysis and tree, quantitative real-time PCR enzyme expression analysis, recombinant expression in Saccharomyces cerevisiae strains ole1 and INVSc1 in microsomes. Santalaceae FADX expressed in yeast has no detectable DELTA12 desaturase activity either acting on native fatty acids or when supplied with exogenous substrates but instead shows cis-DELTA13 desaturation activity on stearolic acid