title: Disruption of the ceramide synthase LOH1 causes spontaneous cell death in Arabidopsis thaliana.
abstract: The bioactive lipid ceramide is produced by the enzyme ceramide synthase, which exists in several isoforms in most eukaryotic organisms. Here, we investigated functional differences between the three ceramide synthase isoforms in Arabidopsis thaliana. The biochemical properties of the three ceramide synthases were investigated by comparing lipid profiles of yeast strains expressing LOH1, LOH2 or LOH3 with those of wild-type and loh1, loh2 and loh3 knockout plants. Expression profiles of the ceramide synthases and of the pathogenesis-related gene PR-1 were investigated by real-time PCR. Each ceramide synthase isoform showed a characteristic preference regarding acyl-CoA chain length as well as sphingoid base hydroxylation, which matches the pattern of ceramide and glucosylceramide species found in leaves. After extended culture under short-day conditions, loh1 plants showed spontaneous cell death accompanied by enhanced expression of PR-1. The levels of free trihydroxy sphingoid bases as well as ceramide and glucosylceramide species with C(16) fatty acid were significantly elevated while species with C(20) -C(28) fatty acids were reduced. These data suggest that spontaneous cell death in the loh1 line is triggered either by the accumulation of free trihydroxy sphingoid bases or ceramide species with C(16) fatty acid.
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.|Present address: metanomics GmbH, Tegeler Weg 33, D-10589 Berlin, Germany.
authors: Philipp
authors: P
authors: Ternes
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.|Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany.
authors: Kirstin
authors: K
authors: Feussner
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors: Stephanie
authors: S
authors: Werner
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors: Jennifer
authors: J
authors: Lerche
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors: Tim
authors: T
authors: Iven
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors: Ingo
authors: I
authors: Heilmann
authors: Department of Biochemistry, Sciences II, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors: Howard
authors: H
authors: Riezman
authors: Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Georg August University, D-37077 Göttingen, Germany.
authors: Ivo
authors: I
authors: Feussner
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D004269:DNA, Bacterial / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017343:Genes, Plant / Q000235:genetics; D005963:Glucosylceramides / Q000378:metabolism; D006900:Hydroxylation; D016254:Mutagenesis, Insertional / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000378:metabolism; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D005963:Glucosylceramides; D010937:Plant Growth Regulators; D012333:RNA, Messenger; C036483:T-DNA; C077262:PR-1 protein, Arabidopsis; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D013110:Sphingosine