title: Rice terpene synthase 20 (OsTPS20) plays an important role in producing terpene volatiles in response to abiotic stresses.
abstract: This study examined the volatile terpenes produced by rice seedlings in response to oxidative stress induced by various abiotic factors. Solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analyses revealed that when exposed to UV-B radiation, rice seedlings emitted a bouquet of monoterpene mixtures in a time-dependent manner. The mixtures comprised limonene, sabinene, myrcene, α-terpinene, β-ocimene, γ-terpinene, and α-terpinolene. Among them, (S)-limonene was the most abundant volatile, discriminated by chiral SPME-GC-MS. The volatile profiles collected from rice plants treated with both γ-irradiation and H2O2 were identical to those observed in the UV-B irradiated plants, thus indicating that the volatile mixtures were specifically produced in response to oxidative stress, particularly in the presence of H2O2. Using a reverse genetics approach, we isolated full-length rice terpene synthase 20 (OsTPS20, 599 amino acids, 69.39 kDa), which was further characterized as an (S)-limonene synthase by removing the N-terminal signal peptide (63 amino acids) of the protein. The recombinant OsTPS20 protein catalyzed the conversion of geranyl diphosphate to (S)-limonene and other minor monoterpenes, essentially covering all of the volatile compounds detected from the plant. Moreover, qRT-PCR revealed that the transcript levels of OsTPS20 were significantly induced in response to oxidative stress, thereby suggesting that OsTPS20 plays a major role in producing terpene volatiles during abiotic stress. Detailed biochemical analyses and the unusual domain characteristics of OsTPS20 are also discussed in this report.
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do, 580-185, Republic of Korea.
authors.forename: Gun Woong
authors.initials: GW
authors.lastname: Lee
authors.forename: Sungbeom
authors.initials: S
authors.lastname: Lee
authors.forename: Moon-Soo
authors.initials: MS
authors.lastname: Chung
authors.forename: Yeon Sim
authors.initials: YS
authors.lastname: Jeong
authors.forename: Byung Yeoup
authors.initials: BY
authors.lastname: Chung
mesh_terms: D000080462:Acyclic Monoterpenes; D000475:Alkenes / Q000378:metabolism; D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D000081008:Bicyclic Monoterpenes; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes / Q000378:metabolism; D005720:Gamma Rays; D008401:Gas Chromatography-Mass Spectrometry; D006861:Hydrogen Peroxide / Q000494:pharmacology; D000077222:Limonene; D039821:Monoterpenes / Q000378:metabolism; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D060888:Real-Time Polymerase Chain Reaction; D060327:Solid-Phase Synthesis Techniques; D013729:Terpenes / Q000378:metabolism*
chemical_list: D000080462:Acyclic Monoterpenes; D000475:Alkenes; D000081008:Bicyclic Monoterpenes; D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D039821:Monoterpenes; D013729:Terpenes; C509595:myrcene; C018669:gamma-terpinene; C035127:sabinene; D000077222:Limonene; D006861:Hydrogen Peroxide; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase; C027009:terpinolene