Combined transgenic expression of Delta 12-desaturase and Delta 12-epoxygenase in high linoleic acid seeds leads to increased accumulation of vernolic acid

The transgenic production of unusual fatty acids in oilseed crops offers an alternative, renewable resource for industry. However, transgenic expression of genes catalysing the synthesis of unusual fatty acids has generally resulted in these fatty acids accumulating at levels significantly below the levels in the wild species from which the genes were sourced. This study reports expression of additional copies of any of three Delta 12-desaturase genes (FAD2) from Crepis palaestina Bornm., cotton (Gossypium hirsutum L.) or Arabidopsis thaliana (L.) Heynh. with C palaestina Delta 12-epoxygenase gene (Cpal2), in an Arabidopsis mutanthaving a significantly higher level of linoleic acid substrate. This resulted in the highest levels of vernolic acid accumulation, 21% of total fatty acids, reported so far in any transgenic plant expressing the Delta 12-epoxygenase. Similarly, the co-expression of C palaestina Cpal2 and a transgenic copy of FAD2 in cotton seed that contains large amounts of linoleic acid substrate also resulted in greater accumulation of vernolic acid in seed than did expression of C palaestina Cpal2 alone.