title: Fatty acid composition of developing sea buckthorn (Hippophae rhamnoides L.) berry and the transcriptome of the mature seed.
abstract: BACKGROUND
  Sea buckthorn (Hippophae rhamnoides L.) is a hardy, fruit-producing plant known historically for its medicinal and nutraceutical properties. The most recognized product of sea buckthorn is its fruit oil, composed of seed oil that is rich in essential fatty acids, linoleic (18:2 ω-6) and α-linolenic (18:3 ω-3) acids, and pulp oil that contains high levels of monounsaturated palmitoleic acid (16:1 ω-7). Sea buckthorn is fast gaining popularity as a source of functional food and nutraceuticals, but currently has few genomic resources; therefore, we explored the fatty acid composition of Canadian-grown cultivars (ssp. mongolica) and the sea buckthorn seed transcriptome using the 454 GS FLX sequencing technology.
  
  
  RESULTS
  GC-MS profiling of fatty acids in seeds and pulp of berries indicated that the seed oil contained linoleic and α-linolenic acids at 33-36% and 30-36%, respectively, while the pulp oil contained palmitoleic acid at 32-42%. 454 sequencing of sea buckthorn cDNA collections from mature seeds yielded 500,392 sequence reads, which identified 89,141 putative unigenes represented by 37,482 contigs and 51,659 singletons. Functional annotation by Gene Ontology and computational prediction of metabolic pathways indicated that primary metabolism (protein>nucleic acid>carbohydrate>lipid) and fatty acid and lipid biosynthesis pathways were highly represented categories. Sea buckthorn sequences related to fatty acid biosynthesis genes in Arabidopsis were identified, and a subset of these was examined for transcript expression at four developing stages of the berry.
  
  
  CONCLUSIONS
  This study provides the first comprehensive genomic resources represented by expressed sequences for sea buckthorn, and demonstrates that the seed oil of Canadian-grown sea buckthorn cultivars contains high levels of linoleic acid and α-linolenic acid in a close to 1:1 ratio, which is beneficial for human health. These data provide the foundation for further studies on sea buckthorn oil, the enzymes involved in its biosynthesis, and the genes involved in the general hardiness of sea buckthorn against environmental conditions.
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Tahira
authors.initials: T
authors.lastname: Fatima
authors.forename: Crystal L
authors.initials: CL
authors.lastname: Snyder
authors.forename: William R
authors.initials: WR
authors.lastname: Schroeder
authors.forename: Dustin
authors.initials: D
authors.lastname: Cram
authors.forename: Raju
authors.initials: R
authors.lastname: Datla
authors.forename: David
authors.initials: D
authors.lastname: Wishart
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Weselake
authors.forename: Priti
authors.initials: P
authors.lastname: Krishna
mesh_terms: D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis*; D005229:Fatty Acids, Monounsaturated / Q000032:analysis; D005638:Fruit / Q000737:chemistry* / Q000254:growth & development; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling; D015723:Gene Library; D031281:Hippophae / Q000737:chemistry* / Q000254:growth & development; D019787:Linoleic Acid / Q000032:analysis; D008969:Molecular Sequence Data; D010938:Plant Oils / Q000737:chemistry*; D012194:RNA-Directed DNA Polymerase; D012525:Saskatchewan; D012639:Seeds / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D059467:Transcriptome / Q000235:genetics*; D017962:alpha-Linolenic Acid / Q000032:analysis
chemical_list: D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D010938:Plant Oils; D017962:alpha-Linolenic Acid; C008757:palmitoleic acid; D019787:Linoleic Acid; D012194:RNA-Directed DNA Polymerase