The Brassicaceae Orychophragmus violaceus (Chinese violet cress, February orchid) is native to China and has been used in intergenic crosses with Brassica napus to study genome stability. Previously published analyses have indicated that the seed oil of this plant is enriched in linoleic acid (18:2) and has low very long-chain fatty acid content. Re-evaluation of O. violaceus oil by thin-layer chromatographic analysis serendipitously revealed the presence of a highly polar oil composition. Structural analyses using methods including NMR and mass spectrometry revealed two C24 dihydroxy fatty acids identified as 7,18-(OH)2-24:1Δ15 and 7,18-(OH)2-24:2Δ15,21 that account for ∼50% of O. violaceus seed oil. Three methods ensured the unambiguous assignment of the connectivity in the structures: pyrrolidide derivatization, von Rudloff degradation and alkene metathesis. The configuration at C-18 was assigned by the comparison of synthetic standards to an alkene cross-metathesis derived fatty acid methyl ester fragment by chiral GC-MS. Collectively, transcriptomic studies of developing O. violaceous seeds, detection of C20 and C22 dihydroxy fatty acid, and the detection of acyl-CoA intermediates revealed a “discontinuous elongation” pathway for hydroxy fatty acid synthesis and the potential for O. violaceus as an industrially relevant oilseed.

Discovery of dihydroxy fatty acids as major components of the seed oil of the brassicaceae Orychophragmus violaceus suggests a variant mode of elongation

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.