PT  - JOURNAL ARTICLE
AU  - Hu, Zhaohui
AU  - Ren, Zhonghai
AU  - Lu, Chaofu
TI  - The Phosphatidylcholine Diacylglycerol Cholinephosphotransferase Is Required for Efficient Hydroxy Fatty Acid Accumulation in Transgenic Arabidopsis
AID  - 10.1104/pp.111.192153
DP  - 2012 Jan 01
TA  - Plant Physiology
PG  - pp.111.192153
4099  - http://www.plantphysiol.org/content/early/2012/02/27/pp.111.192153.short
4100  - http://www.plantphysiol.org/content/early/2012/02/27/pp.111.192153.full
AB  - We previously identified an enzyme, phosphatidylcholine diacylglycerol cholinephosphotransferase (PDCT), that plays an important role in directing fatty acyl fluxes during triacylglycerol (TAG) biosynthesis. The PDCT mediates a symmetrical inter-conversion between phosphatidylcholine (PC) and diacylglycerol (DAG), thus enriching PC-modified fatty acids in the DAG pool prior to forming TAG. We show here that PDCT is required for efficient metabolism of engineered hydroxy fatty acids in Arabidopsis seeds. When a fatty acid hydroxylase (FAH12) from castor (Ricinus communis) was expressed in Arabidopsis seeds, the PDCT-deficient mutant accumulated only about half the amount of hydroxy fatty acids compared to that in the wild type seeds. We also isolated a PDCT from castor encoded by the RcROD1 gene. Seed-specific co-expression of this enzyme significantly increased hydroxy fatty acid accumulation in wild type-FAH12 and in a previously produced transgenic Arabidopsis line co-expressing a castor diacylglycerol acyltransferase 2 (RcDGAT2). Analyzing the TAG molecular species and regiochemistry, along with analysis of fatty acid composition in TAG and PC during seed development, indicate that PDCT acts in planta to enhance the fluxes of fatty acids through PC and enrich the hydroxy fatty acids in DAG, and thus in TAG. In addition, PDCT partially restores the oil content that is decreased in FAH12 expressing seeds. Our results add a new gene in the genetic toolbox for efficiently engineering unusual fatty acids in transgenic oilseeds.