Expression of Mucor circinelloides gene for Δ6 desaturase results in the accumulation of high levels of γ-linolenic acid in transgenic tobacco

γ-Linolenic acid (GLA; C18:3 Δ6,9,12) is a nutritionally important fatty acid (FA) playing a vital role in biological structures and cellular functions, which is not produced in oil seed crops. Many oil seed plants, however, produce significant quantities of linoleic acid, a FA that could be converted into GLA by the enzyme Δ6 desaturase, if it is present. As a first step to produce GLA in oil seed crops, we isolated a cDNA encoding the Δ6-FA desaturase from filamentous fungus Mucor circinelloides M29. Expression of this gene in transgenic tobacco resulted in the accumulation of GLA to the levels of 23.1% of the total FA. The results suggested that it is feasible to introduce the M. circinelloides Δ6 desaturase gene into conventional oil crop to produce a large amount of GLA for functional foods and pharmaceutical products.