title: Sphingolipid metabolism is strikingly different between pollen and leaf in Arabidopsis as revealed by compositional and gene expression profiling.
abstract: Although sphingolipids are essential for male gametophytic development in Arabidopsis thaliana, sphingolipid composition and biosynthetic gene expression have not been previously examined in pollen. In this report, electrospray ionization (ESI)-MS/MS was applied to characterization of sphingolipid compositional profiles in pollen isolated from wild type Arabidopsis Col-0 and a long-chain base (LCB) Δ4 desaturase mutant. Pollen fractions were highly enriched in glucosylceramides (GlcCer) relative to levels previously reported in leaves. Accompanying the loss of the Δ4 unsaturated LCB sphingadiene (d18:2) in the Δ4 desaturase mutant was a 50% reduction in GlcCer concentrations. In addition, pollen glycosylinositolphosphoceramides (GIPCs) were found to have a complex array of N-acetyl-glycosylated GIPCs, including species with up to three pentose units that were absent from leaf GIPCs. Underlying the distinct sphingolipid composition of pollen, genes for key biosynthetic enzymes for GlcCer and d18:2 synthesis and metabolism were more highly expressed in pollen than in leaves or seedlings, including genes for GlcCer synthase (GCS), sphingoid base C-4 hydroxylase 2 (SBH2), LCB Δ8 desaturases (SLD1 and SLD2), and LOH2 ceramide synthase (LOH2). Overall, these findings indicate strikingly divergent sphingolipid metabolism between pollen and leaves in Arabidopsis, the significance of which remains to be determined.
authors: Center for Plant Science Innovation and Department of Biochemistry, E318 Beadle Center, 1901 Vine Street, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: kyle.luttgeharm@huskers.unl.edu.
authors: Kyle D
authors: KD
authors: Luttgeharm
authors: Center for Plant Science Innovation and Department of Biochemistry, E318 Beadle Center, 1901 Vine Street, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: akimberlin1@huskers.unl.edu.
authors: Athen N
authors: AN
authors: Kimberlin
authors: Center for Plant Science Innovation and Department of Biochemistry, E318 Beadle Center, 1901 Vine Street, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: rcahoon2@unl.edu.
authors: Rebecca E
authors: RE
authors: Cahoon
authors: Department of Chemistry, 710 Hamilton Hall, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: rcerny1@unl.edu.
authors: Ronald L
authors: RL
authors: Cerny
authors: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden AL5 2JQ, United Kingdom. Electronic address: johnathan.napier@rothamsted.ac.uk.
authors: Johnathan A
authors: JA
authors: Napier
authors: Center for Plant Science Innovation and Department of Biochemistry, E318 Beadle Center, 1901 Vine Street, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: jemarkham@unl.edu.
authors: Jennifer E
authors: JE
authors: Markham
authors: Center for Plant Science Innovation and Department of Biochemistry, E318 Beadle Center, 1901 Vine Street, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: ecahoon2@unl.edu.
authors: Edgar B
authors: EB
authors: Cahoon
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D020869:Gene Expression Profiling; D005963:Glucosylceramides / Q000032:analysis; D018515:Plant Leaves / Q000378:metabolism*; D011058:Pollen / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism*
chemical_list: D005963:Glucosylceramides; D013107:Sphingolipids
keywords: Arabidopsis thaliana; Brassicaceae; Glucosylceramide; Glycosylinositolphosphoceramide; Lipidomics; Pollen; Sphingolipid