PURPOSE: To obtain a new plant seed useful to vary the fatty acid content of seed oil. CONSTITUTION: This new plant seed contains a yeastδ-9-desaturase gene and a means of manifesting the gene in the seed, e.g. a phaseol in promoter. It is obtd. by transformation by which extraneous DNA is added to the undenatured DNA of a plant seed such as a seed of Brassic or Zea mays in the form of a yeastδ-9-desaturase and a promoter for the gene.