title: Identification and expression of a stearoyl-ACP desaturase gene responsible for oleic acid accumulation in Xanthoceras sorbifolia seeds.
abstract: Xanthoceras sorbifolia Bunge is an oilseed tree that grows well on barren lands in dry climate. Its seeds contain a large amount of oil rich in oleic acid (18:1(Δ9)) and linoleic acid (18:2(Δ9, 12)). However, the molecular regulation of oil biosynthesis in X. sorbifolia seeds is poorly understood. Stearoyl-ACP desaturase (SAD, EC 1.14.99.6) is a plastid-localized soluble desaturase that catalyzes the conversion of stearic acid (18:0) to oleic acid, which plays a key role in determining the ratio of saturated to unsaturated fatty acids. In this study, a full-length cDNA of XsSAD was isolated from developing X. sorbifolia embryos. The XsSAD open reading frame had 1194-bp, encoding a polypeptide of 397 amino acids. XsSAD expression in Escherichia coli cells resulted in increased 18:1(Δ9) level, confirming the biological activity of the enzyme encoded by XsSAD. XsSAD expression in Arabidopsis ssi2 mutants partially restored the morphological phenotype and effectively increased the 18:1(Δ9) level. The levels of other unsaturated fatty acids synthesized with 18:1(Δ9) as the substrate also increased to some degree. XsSAD in X. sorbifolia had a much higher expression in embryos than in leaves and petals. XsSAD expression also correlated well with the oleic acid, unsaturated fatty acid, and total fatty acid levels in developing embryos. These data suggested that XsSAD determined the synthesis of oleic acid and contributed to the accumulation of unsaturated fatty acid and total oil in X. sorbifolia seeds. A preliminary tobacco rattle virus-based virus-induced gene silencing system established in X. sorbifolia can also be helpful for further analyzing the functions of XsSAD and other oil synthesis-related genes in woody plants.
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: momozhaona@163.com.
authors.forename: Na
authors.initials: N
authors.lastname: Zhao
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: jidan0214@qq.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: liqiuqi994@gmail.com.
authors.forename: Qiuqi
authors.initials: Q
authors.lastname: Li
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: lirf13@163.com.
authors.forename: Rufang
authors.initials: R
authors.lastname: Li
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: xiaxl@bjfu.edu.cn.
authors.forename: Xinli
authors.initials: X
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, 100101, China. Electronic address: Qinxw@ioz.ac.cn.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Qin
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China. Electronic address: guohh@bjfu.edu.cn.
authors.forename: Huihong
authors.initials: H
authors.lastname: Guo
mesh_terms: D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D019301:Oleic Acid / Q000096:biosynthesis* / Q000235:genetics; D010938:Plant Oils / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D029631:Sapindaceae / Q000201:enzymology / Q000235:genetics; D012639:Seeds / Q000201:enzymology / Q000235:genetics
chemical_list: D010938:Plant Oils; D010940:Plant Proteins; D011994:Recombinant Proteins; D019301:Oleic Acid; D044943:Fatty Acid Desaturases
keywords: Functional and expression analysis; Oleic acid; Seed oil; Stearoyl-ACP desaturase; Unsaturated fatty acid; Xanthoceras sorbifolia Bunge