title: Phospholipid:diacylglycerol acyltransferase-mediated triacylglycerol biosynthesis is crucial for protection against fatty acid-induced cell death in growing tissues of Arabidopsis.
abstract: Phospholipid:diacylglycerol acyltransferase (PDAT) and diacylglycerol:acyl CoA acyltransferase play overlapping roles in triacylglycerol (TAG) assembly in Arabidopsis, and are essential for seed and pollen development, but the functional importance of PDAT in vegetative tissues remains largely unknown. Taking advantage of the Arabidopsis tgd1-1 mutant that accumulates oil in vegetative tissues, we demonstrate here that PDAT1 is crucial for TAG biosynthesis in growing tissues. We show that disruption of PDAT1 in the tgd1-1 mutant background causes serious growth retardation, gametophytic defects and premature cell death in developing leaves. Lipid analysis data indicated that knockout of PDAT1 results in increases in the levels of free fatty acids (FFAs) and diacylglycerol. In vivo ¹⁴C-acetate labeling experiments showed that, compared with wild-type, tgd1-1 exhibits a 3.8-fold higher rate of fatty acid synthesis (FAS), which is unaffected by disruption or over-expression of PDAT1, indicating a lack of feedback regulation of FAS in tgd1-1. We also show that detached leaves of both pdat1-2 and tgd1-1 pdat1-2 display increased sensitivity to FFA but not to diacylglycerol. Taken together, our results reveal a critical role for PDAT1 in mediating TAG synthesis and thereby protecting against FFA-induced cell death in fast-growing tissues of plants.
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
authors.forename: Jilian
authors.initials: J
authors.lastname: Fan
authors.forename: Chengshi
authors.initials: C
authors.lastname: Yan
authors.forename: Changcheng
authors.initials: C
authors.lastname: Xu
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D051048:Diacylglycerol O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D008055:Lipids / Q000032:analysis; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D029681:Arabidopsis Proteins; D005230:Fatty Acids, Nonesterified; D008055:Lipids; D026901:Membrane Transport Proteins; C475468:TGD1 protein, Arabidopsis; D014280:Triglycerides; D000217:Acyltransferases; C000591695:PDAT1 protein, Arabidopsis; D051048:Diacylglycerol O-Acyltransferase
keywords: Arabidopsis thaliana; free fatty acid; phospholipid:diacylglycerol acyltransferase; premature cell death; triacylglycerol