PCT No. PCT/GB96/01894 Sec. 371 Date Jan. 20, 1998 Sec. 102(e) Date Jan. 20, 1998 PCT Filed Aug. 6, 1996 PCT Pub. No. WO97/07222 PCT Pub. Date Feb. 27, 1997The capacity of a plant to produce fatty acids is modulated by controlling the expression of a gene specifying the acetyl CoA carboxylase biotin carboxyl carrier protein. Modulation may comprise increasing the expression of the gene by insertion of additional copies into the genome or inhibiting expression by insertion of an antisense or cosuppression vector directed against the endogenous gene.