title: XsFAD2 gene encodes the enzyme responsible for the high linoleic acid content in oil accumulated in Xanthoceras sorbifolia seeds.
abstract: BACKGROUND
  Xanthoceras sorbifolia Bunge is a valuable oilseed tree that has linoleic acid-rich seed oil. Microsomal oleate desaturase (FAD2; EC 1.3.1.35) is responsible for the conversion of oleic acid to linoleic acid during fatty acid synthesis. In this study, XsFAD2 was cloned from developing embryos of X. sorbifolia.
  
  
  RESULTS
  XsFAD2 contained three histidine boxes, a C-terminal endoplasmic reticulum retrieval motif, and five putative transmembrane domains representing the characteristics of membrane-bound fatty acid desaturase. XsFAD2 expression in yeast cells resulted in linoleic acid (18:2) and palmitolinoleic acid (16:2) production, confirming the biological activity of the enzyme encoded by XsFAD2. These fatty acids are not normally present in wild-type yeast. Phylogenetic analysis indicated that XsFAD2 is located in a subgroup of FAD2 enzymes specifically or highly expressed in developing seeds. The expression level of XsFAD2 in seeds was much higher than those in leaves and petals. Furthermore, XsFAD2 expression pattern correlated well with linoleic acid accumulated in seeds.
  
  
  CONCLUSIONS
  Results suggested that XsFAD2 is responsible for the high linoleic acid content in X. sorbifolia seed oil. This study provides insight on the regulation mechanism of fatty acid synthesis in X. sorbifolia seeds and a valuable gene for improving the oil quality in oilseed trees.
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, National Engineering Laboratory for Tree Breeding; Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education; The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of State Forestry Administration, No. 35, Tsing Hua East Road, Haidian District, Beijing, 100083, China.
authors.forename: Hui-Hong
authors.initials: HH
authors.lastname: Guo
authors.forename: Qiu-Qi
authors.initials: QQ
authors.lastname: Li
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Hu
authors.forename: Wen-Hong
authors.initials: WH
authors.lastname: Deng
authors.forename: Xin-Li
authors.initials: XL
authors.lastname: Xia
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Gao
mesh_terms: D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D017343:Genes, Plant; D019787:Linoleic Acid / Q000096:biosynthesis / Q000235:genetics*; D019301:Oleic Acid / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics* / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D029631:Sapindaceae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000378:metabolism
chemical_list: D010938:Plant Oils; D010940:Plant Proteins; D019301:Oleic Acid; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; C021904:Phosphatidylcholine desaturase; D044925:Oxidoreductases Acting on CH-CH Group Donors
keywords: Xanthoceras sorbifolia Bunge; gene expression; linoleic acid accumulation; microsomal oleate desaturase gene; seed oil