Characterisation of the FAD2 gene family from Hiptage benghalensis: A ricinoleic acid accumulating plant

We have characterised the FAD2 gene family from Hiptage benghalensis, a tropical plant that accumulates high levels of ricinoleic acid in its seeds. Functional characterisation of six FAD2 gene family members showed that two of them were capable of functioning as Delta 12-hydroxylases while the other FAD2 members were confirmed to be Delta 12-desaturases. The Delta 12-hydroxylation function of these two genes was confirmed in yeast cells, using C16:1(Delta 9) and C18:1(Delta 9) monounsaturated fatty acids as substrates. These Delta 12-hydroxylases, like the other Delta 12-hydroxylases previously cloned from plants Ricinus communis (castor), Physaria fendleri and fungus Claviceps purpurea, also showed some Delta 12-desaturase activity. The hydroxylation activity of the two Hiptage hydroxylases was further confirmed by their expression in the Arabidopsis fad2/fae1 double mutant where they were able to produce equivalent or higher levels hydroxylated fatty acids in the seed oil when compared with the other known hydroxylases. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.