Heterologous production of GLA and SDA by expression of an Echium plantagineum Δ6-desaturase gene

A Δ6-desaturase gene was isolated from Echium plantagineum and its catalytic activity confirmed by heterologous expression in tobacco plants and yeast. The results demonstrate that this enzyme (EplD6Des) is able to carry out Δ6-desaturation of the ω6 and ω3 fatty acid substrates LA and ALA with an apparent preference for LA, but does not perform Δ5- or Δ8-desaturation. Transgenic expression of the EplD6Des gene in Arabidopsis seeds showed a relative desaturation of LA and ALA similar to that observed in the source plant. PCR random mutagenesis of the EplD6Des gene identified mutations outside the conserved histidine boxes that dramatically reduced the enzyme activity.