industrial crops and products 29 ( 2 0 0 9 ) 530–535 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/indcrop Investigation of diacylglycerol acyltransferase (DGAT) activity of microsomes from the seeds of three euphorbs M.J. Pascual-Villalobos a,∗ , M.D. López a , M.T. Castells b , M.D. Alcázar c a Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), Estación Sericícola, c/Mayor s/n, 30150 La Alberca, Murcia, Spain b Servicio de Apoyo a la Investigación (SAI), Análisis de Imagen, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain c Servicio de Apoyo a la Investigación (SAI), Radioprotección y Residuos, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain article info Article history: Received 30 July 2008 Received in revised form 14 October 2008 Accepted 14 October 2008 Keywords: Ricinus communis Euphorbia lathyris Euphorbia lagascae Unusual fatty acids Triacylglycerols 1,2-Diacylglycerol acyltransferase (DGAT) abstract Unusual fatty acids such as ricinoleate (12-hydroxyoleic acid) occurring in Ricinus communis L. or vernoleate (12,13-epoxyoleic acid) occurring in Euphorbia lagascae L. are suitable for industrial uses. Euphorbia lathyris L. is also a potential new oilseed crop on account of its high content of oleic acid in the seeds. The objective of this work was to test in vitro the preferences of E. lathyris microsomes for its native substrates (oleoyl-CoA and diolein) and to compare with R. communis and E. lagascae systems. The diacylglycerol acyltransferase (DGAT) catalyses the final step in transferring a fatty acid moiety to a diacylglycerol (DAG) into a triacylglycerol (TAG). To study the DGAT activity in microsomes of the three euphorbs: (1) plants of the three species were grown in a glasshouse at Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (Murcia, Spain), (2) endosperms were removed from developing seeds and the tissue was extracted, (3) in vitro DGAT assays using [ 14 C]-oleoyl-CoA with or without 1,2-diolein were carried out and 4) labelled TAG were recorded using a molecular imager and a scintillation counter. Incorporation of [ 14 C]-oleoyl into TAG was greater in R. communis and E. lathyris (72–89% of total TAG) than in E. lagascae. Adding exogenous 1,2-diolein (1 mM) to E. lagascae microsomes increased the amount of labelled TAG to 39%, suggesting that other acyl groups were being incorporated as well. R. communis and E. lagascae microsomes gave more-polar radiolabelled TAGs than E. lathyris possibly because endogenous DAGs (not 1,2-diolein) were being used in the reaction. Although E. lathyris microsomes showed specificity towards 1,2-diolein as a substrate, the preparations from R. communis, E. lagascae and E. lathyris were able to use the acyl donor and acyl receptor, possibly suggesting that DGAT enzymes would not be a limiting factor to engineer Euphorbiaceae crops with functionalized fatty acids. © 2008 Elsevier B.V. All rights reserved. 1. Introduction For industrial uses, fatty acids with hydroxy, epoxy or unusual positions of desaturation are desired (Meier zu Beerentrup ∗ Corresponding author. E-mail address: mjesus.pascual@carm.es (M.J. Pascual-Villalobos). and Röbbelen, 1987). Castor oil containing up to 90% ricinoleic acid (12-hydroxyoleic acid) is obtained from Ricinus communis L. (Euphorbiaceae) and it is traded in quantity. Kleiman et al. (1965) in a survey of euphorb seed oils identified one species 0926-6690/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2008.10.005