title: A 2-Oxoglutarate-Dependent Dioxygenase Mediates the Biosynthesis of Glucoraphasatin in Radish.
abstract: Glucosinolates (GSLs) are secondary metabolites whose degradation products confer intrinsic flavors and aromas to Brassicaceae vegetables. Several structures of GSLs are known in the Brassicaceae, and the biosynthetic pathway and regulatory networks have been elucidated in Arabidopsis (Arabidopsis thaliana). GSLs are precursors of chemical defense substances against herbivorous pests. Specific GSLs can act as feeding blockers or stimulants, depending on the pest species. Natural selection has led to diversity in the GSL composition even within individual species. However, in radish (Raphanus sativus), glucoraphasatin (4-methylthio-3-butenyl glucosinolate) accounts for more than 90% of the total GSLs, and little compositional variation is observed. Because glucoraphasatin is not contained in other members of the Brassicaceae, like Arabidopsis and cabbage (Brassica oleracea), the biosynthetic pathways for glucoraphasatin remain unclear. In this report, we identified and characterized a gene encoding GLUCORAPHASATIN SYNTHASE 1 (GRS1) by genetic mapping using a mutant that genetically lacks glucoraphasatin. Transgenic Arabidopsis, which overexpressedGRS1cDNA, accumulated glucoraphasatin in the leaves.GRS1encodes a 2-oxoglutarate-dependent dioxygenase, and it is abundantly expressed in the leaf. To further investigate the biosynthesis and transportation of GSLs in radish, we grafted agrs1plant onto a wild-type plant. The grafting experiment revealed a leaf-to-root long-distance glucoraphasatin transport system in radish and showed that the composition of GSLs differed among the organs. Based on these observations, we propose a characteristic biosynthesis pathway for glucoraphasatin in radish. Our results should be useful in metabolite engineering for breeding of high-value vegetables.
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.); tkaki@affrc.go.jp.|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.) tkaki@affrc.go.jp.
authors.forename: Tomohiro
authors.identifier: 0000-0002-3636-6616
authors.initials: T
authors.lastname: Kakizaki
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kitashiba
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Zhongwei
authors.identifier: 0000-0002-8955-1153
authors.initials: Z
authors.lastname: Zou
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Nobuko
authors.initials: N
authors.lastname: Fukino
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ohara
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishio
authors.affiliation: Division of Vegetable Breeding, Institute of Vegetable and Floriculture Science, NARO, Ano, Tsu, Mie 514-2392, Japan (T.K., N.F., T.O., M.I.).|and Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai, Miyagi 980-0845, Japan (H.K., Z.Z., F.L., T.N.).
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ishida
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D053898:Biosynthetic Pathways / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D049308:Dioxygenases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005961:Glucosinolates / Q000032:analysis / Q000096:biosynthesis*; D007656:Ketoglutaric Acids / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods; D009154:Mutation; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D031224:Raphanus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017386:Sequence Homology, Amino Acid
chemical_list: C507366:4-methylthio-3-butenyl glucosinolate; D005961:Glucosinolates; D007656:Ketoglutaric Acids; D049308:Dioxygenases