title: P-HYDROXYPHENYLPYRUVATE DIOXYGENASE from Medicago sativa is involved in vitamin E biosynthesis and abscisic acid-mediated seed germination.
abstract: P-HYDROXYPHENYLPYRUVATE DIOXYGENASE (HPPD) is the first committed enzyme involved in the biosynthesis of vitamin E, and is characterized by catalyzing the conversion of p-hydroxyphenyl pyruvate (HPP) to homogentisic acid (HGA). Here, an HPPD gene was cloned from Medicago sativa L. and designated MsHPPD, which was expressed at high levels in alfalfa leaves. PEG 6000 (polyethylene glycol), NaCl, abscisic acid and salicylic acid were shown to significantly induce MsHPPD expression, especially in the cotyledons and root tissues. Overexpression of MsHPPD was found to significantly increase the level of β-tocotrienol and the total vitamin E content in Arabidopsis seeds. Furthermore, these transgenic Arabidopsis seeds exhibited an accelerated germination time, compared with wild-type seeds under normal conditions, as well as under NaCl and ABA treatments. Meanwhile, the expression level of several genes associated with ABA biosynthesis (NCED3, NCED5 and NCED9) and the ABA signaling pathway (RAB18, ABI3 and ABI5) were significantly down-regulated in MsHPPD-overexpressing transgenic lines, as well as the total free ABA content. Taken together, these results demonstrate that MsHPPD functions not only in the vitamin E biosynthetic pathway, but also plays a critical role in seed germination via affecting ABA biosynthesis and signaling.
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
authors.forename: Jishan
authors.initials: J
authors.lastname: Jiang
authors.affiliation: National Animal Husbandry Service, Ministry of Agriculture, Beijing 100125, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Ban
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
authors.forename: Yudi
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.|College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Huang
authors.affiliation: National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Jinfang
authors.initials: J
authors.lastname: Chu
authors.affiliation: National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Fang
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
authors.forename: Zan
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
authors.forename: Hongwen
authors.initials: H
authors.lastname: Gao
authors.affiliation: Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
mesh_terms: D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D003001:Cloning, Molecular; D019295:Computational Biology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects* / Q000235:genetics; D000455:Medicago sativa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics; D030821:Plants, Genetically Modified; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000187:drug effects; D014810:Vitamin E / Q000096:biosynthesis*
chemical_list: D014810:Vitamin E; D000040:Abscisic Acid; D015111:4-Hydroxyphenylpyruvate Dioxygenase