This invention relates to nucleic acid sequences coding for a Lunaria annua, Cardamine graeca or Teesdalia nudicaulis fatty acid elongase, yeast cells expressing the genes/enzymes, plants themselves and cells of such plants and seeds which contain a heterologous gene coding for a L. annua, C. graeca or T. nudicaulis fatty acid elongase gene, the plant or seed being capable of producing increased proportion of a very long chain monounsaturated fatty acid, especially nervonic acid and eicosenoic acid, beyond that of a control plant or seed lacking the heterologous FAE gene or genes.