title: Arabidopsis mutants of sphingolipid fatty acid α-hydroxylases accumulate ceramides and salicylates.
abstract: In Arabidopsis, the fatty acid moiety of sphingolipids is mainly α-hydroxylated. The consequences of a reduction in this modification were analysed. Mutants of both Fatty Acid Hydroxylase genes (AtFAH1 and AtFAH2) were analysed for sphingolipid profiles. To elucidate further consequences of the mutations, metabolic analyses were performed and the influence on pathogen defence was determined. Ceramide and glucosylceramide profiles of double-mutant plants showed a reduction in sphingolipids with α-hydroxylated fatty acid moieties, and an accumulation of sphingolipids without these moieties. In addition, the free trihydroxylated long-chain bases and ceramides were increased by five- and ten-fold, respectively, whereas the amount of glucosylceramides was decreased by 25%. Metabolite analysis of the double mutant revealed salicylates as enriched metabolites. Infection experiments supported the metabolic changes, as the double mutant showed an enhanced disease-resistant phenotype for infection with the obligate biotrophic pathogen Golovinomyces cichoracearum. In summary, these results suggest that fatty acid hydroxylation of ceramides is important for the biosynthesis of complex sphingolipids. Its absence leads to the accumulation of long-chain bases and ceramides as their precursors. This increases salicylate levels and resistance towards obligate biotrophic fungal pathogens, confirming a role of sphingolipids in salicylic acid-dependent defence reactions.
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: König
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Feussner
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany.
authors.forename: Marnie
authors.initials: M
authors.lastname: Schwarz
authors.affiliation: Department of Bioinformatics, Institute of Microbiology and Genetics, Georg-August-University, Goldschmidtstr. 1, 37077, Göttingen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kaever
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Iven
authors.affiliation: Department of Bioinformatics, Institute of Microbiology and Genetics, Georg-August-University, Goldschmidtstr. 1, 37077, Göttingen, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Landesfeind
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ternes
authors.affiliation: Department of Crop Sciences, Molecular Phytopathology and Mycotoxin Research Group, Georg-August-University, Grisebachstr. 6, 37077, Göttingen, Germany.
authors.forename: Petr
authors.initials: P
authors.lastname: Karlovsky
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Lipka
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
authors.forename: Ivo
authors.initials: I
authors.lastname: Feussner
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001203:Ascomycota / Q000472:pathogenicity; D002518:Ceramides / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006900:Hydroxylation; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology; D020156:Salicylic Acid / Q000378:metabolism; D013107:Sphingolipids / Q000737:chemistry* / Q000378:metabolism; D020172:Verticillium / Q000472:pathogenicity
chemical_list: D029681:Arabidopsis Proteins; D002518:Ceramides; D013107:Sphingolipids; D006899:Mixed Function Oxygenases; C575859:fatty acid 2-hydroxylase 1, Arabidopsis; C575860:fatty acid 2-hydroxylase 2, Arabidopsis; D020156:Salicylic Acid