Novel compositions and methods are provided for modifying the lipid content of plant tissues of interest, including leaf, root, fruit and seed. The methods involve transforming a plant cell of interest with an expression cassette functional in a plant cell comprising a transcriptional and translational initiation regulatory region, joined in reading frame 5' to a DNA sequence encoding an enzyme capable of modulating the production of fatty acids, and translational and transcriptional termination regions. Expression of the enzyme provides for an increase in fatty acid biosynthesis as a result of altered concentrations of substrate for enzymes involved in fatty acid biosynthesis. Of particular interest is the selective control of lipid production in plant tissues such as leaves, root, fruit and seed.