The present invention relates to fungal .DELTA.-15 fatty acid desaturases
that are able to catalyze the conversion of linoleic acid (18:2, LA) to
alpha-linolenic acid (18:3, ALA). Nucleic acid sequences encoding the
desaturases, nucleic acid sequences which hybridize thereto, DNA
constructs comprising the desaturase genes, and recombinant host plants
and microorganisms expressing increased levels of the desaturases are
described. Methods of increasing production of specific omega-3 and
omega-6 fatty acids by over-expression of the .DELTA.-15 fatty acid
desaturases are also described herein.
