Metabolism and accumulation of hydroxylated fatty acids by castor (Ricinus comunis) seed microsomes

Castor beans accumulate large amounts of triacylglycerols (TAGs) in the seed endosperm. This oil contains hydroxylated ricinoleic levels close to 90%, which is unique among oil seeds. The capacity to accumulate such high levels of such an unusual fatty acids is due to its specific accumulation and channeling. Here, the ability of the castor biosynthetic machinery to accumulate unusual fatty acids in the form of TAGs was investigated, focusing on ricinoleic acid and the structurally analogous lesquerolic and coriolic fatty acids. The metabolism of different radioactive precursors in active membrane fractions from castor bean's were studied, and the rates and accumulation of these fatty acids provided evidence of the different mechanisms involved in the accumulation of hydroxylated fatty acids in this species. In particular, these studies highlighted the potential of castor to accumulate unusual fatty acids other than ricinoleic acid, showing that castor endosperm can efficiently accumulate lesquerolic acid.