title: Castor phospholipid:diacylglycerol acyltransferase facilitates efficient metabolism of hydroxy fatty acids in transgenic Arabidopsis.
abstract: Producing unusual fatty acids (FAs) in crop plants has been a long-standing goal of green chemistry. However, expression of the enzymes that catalyze the primary synthesis of these unusual FAs in transgenic plants typically results in low levels of the desired FA. For example, seed-specific expression of castor (Ricinus communis) fatty acid hydroxylase (RcFAH) in Arabidopsis (Arabidopsis thaliana) resulted in only 17% hydroxy fatty acids (HFAs) in the seed oil. In order to increase HFA levels, we investigated castor phospholipid:diacylglycerol acyltransferase (PDAT). We cloned cDNAs encoding three putative PDAT enzymes from a castor seed cDNA library and coexpressed them with RcFAH12. One isoform, RcPDAT1A, increased HFA levels to 27%. Analysis of HFA-triacylglycerol molecular species and regiochemistry, along with analysis of the HFA content of phosphatidylcholine, indicates that RcPDAT1A functions as a PDAT in vivo. Expression of RcFAH12 alone leads to a significant decrease in FA content of seeds. Coexpression of RcPDAT1A and RcDGAT2 (for diacylglycerol acyltransferase 2) with RcFAH12 restored FA levels to nearly wild-type levels, and this was accompanied by a major increase in the mass of HFAs accumulating in the seeds. We show the usefulness of RcPDAT1A for engineering plants with high levels of HFAs and alleviating bottlenecks due to the production of unusual FAs in transgenic oilseeds.
authors.affiliation: Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340, USA.
authors.forename: Harrie
authors.initials: H
authors.lastname: van Erp
authors.forename: Philip D
authors.initials: PD
authors.lastname: Bates
authors.forename: Julie
authors.initials: J
authors.lastname: Burgal
authors.forename: Jay
authors.initials: J
authors.lastname: Shockey
authors.forename: John
authors.initials: J
authors.lastname: Browse
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D002367:Ricinus communis / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D005227:Fatty Acids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D006880:Hydroxy Acids / Q000378:metabolism*; D010938:Plant Oils / Q000737:chemistry; D030821:Plants, Genetically Modified / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D012639:Seeds / Q000737:chemistry; D014170:Transformation, Genetic
chemical_list: D005227:Fatty Acids; D006880:Hydroxy Acids; D010938:Plant Oils; D018749:RNA, Plant; D000217:Acyltransferases; C426836:phospholipid diacylglycerol acyltransferase