Linoleic acid is converted into .gamma.-linolenic acid by the enzyme .DELTA.6-desaturase. The present invention is directed to an isolated nucleic acid comprising the .DELTA.6-desaturase gene. More particularly, the isolated nucleic acid comprises the promoter, coding region and termination regions of the .DELTA.6-desaturase gene. The present invention provides recombinant constructions comprising the .DELTA.6-desaturase coding region in functional combination with heterologous regulatory sequences. The nucleic acids and recombinant constructions of the instant invention are useful in the production of GLA in transgenic organisms.