title: CYP74B24 is the 13-hydroperoxide lyase involved in biosynthesis of green leaf volatiles in tea (Camellia sinensis).
abstract: Green leaf volatiles (GLVs) are C6-aliphatic aldehydes/alcohols/acetates, and biosynthesized from the central precursor fatty acid 13-hydroperoxides by 13-hydroperoxide lyases (HPLs) in various plant species. While GLVs have been implicated as defense compounds in plants, GLVs give characteristic grassy note to a bouquet of aroma in green tea, which is manufactured from young leaves of Camellia sinensis. Here we identify three HPL-related genes from C. sinensis via RNA-Sequencing (RNA-Seq) in silico, and functionally characterized a candidate gene, CYP74B24, as a gene encoding tea HPL. Recombinant CYP74B24 protein heterologously expressed in Escherichia coli specifically produced (Z)-3-hexenal from 13-HPOT with the optimal pH 6.0 in vitro. CYP74B24 gene was expressed throughout the aerial organs in a rather constitutive manner and further induced by mechanical wounding. Constitutive expression of CYP74B24 gene in intact tea leaves might account for low but substantial and constitutive formation of a subset of GLVs, some of which are stored as glycosides. Our results not only provide novel insights into the biological roles that GLVs play in tea plants, but also serve as basis for the improvement of aroma quality in tea manufacturing processes.
authors.affiliation: Research Institute, Suntory Global Innovation Center Ltd, 8-1-1 Seika-dai, Seika, Soraku, Kyoto 619-0238, Japan. Electronic address: eiichiro_ono@suntory.co.jp.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Ono
authors.affiliation: Graduate School of Medicine and Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. Electronic address: r038ge@yamaguchi-u.ac.jp.
authors.forename: Taiki
authors.initials: T
authors.lastname: Handa
authors.affiliation: Graduate School of Medicine and Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. Electronic address: takaori@yamaguchi-u.ac.jp.
authors.forename: Takao
authors.initials: T
authors.lastname: Koeduka
authors.affiliation: Research Institute, Suntory Global Innovation Center Ltd, 8-1-1 Seika-dai, Seika, Soraku, Kyoto 619-0238, Japan. Electronic address: hiromi_toyonaga@skal.suntory.co.jp.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Toyonaga
authors.affiliation: Graduate School of Medicine and Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. Electronic address: t014uj@yamaguchi-u.ac.jp.
authors.forename: Moataz M
authors.initials: MM
authors.lastname: Tawfik
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seika-dai, Seika, Soraku, Kyoto 619-0238, Japan. Electronic address: shiraishi@sunbor.or.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Shiraishi
authors.affiliation: Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seika-dai, Seika, Soraku, Kyoto 619-0238, Japan. Electronic address: murata-j@sunbor.or.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Murata
authors.affiliation: Graduate School of Medicine and Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. Electronic address: matsui@yamaguchi-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsui
mesh_terms: D000085:Acetates / Q000378:metabolism; D000446:Aldehyde-Lyases / Q000235:genetics / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism; D000595:Amino Acid Sequence; D028241:Camellia sinensis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D008042:Linolenic Acids / Q000378:metabolism; D008054:Lipid Peroxides / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D013662:Tea; D055549:Volatile Organic Compounds / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000085:Acetates; D000447:Aldehydes; D008042:Linolenic Acids; D008054:Lipid Peroxides; D010940:Plant Proteins; D011994:Recombinant Proteins; D013662:Tea; D055549:Volatile Organic Compounds; C057375:13-hydroperoxy-9,11,15-octadecatrienoic acid; C586688:3-hexenal; D003577:Cytochrome P-450 Enzyme System; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase
keywords: CYP74; Camellia sinensis; Green leaf volatile; Hydroperoxide lyase; Tea