title: Direct suppression of a rice bacterial blight (Xanthomonas oryzae pv. oryzae) by monoterpene (S)-limonene.
abstract: Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a severe disease of rice plants. Upon pathogen infection, rice biosynthesizes phytoalexins, including diterpenoids such as momilactones, phytocassanes, and oryzalexins. However, information on headspace volatiles in response to Xoo infection is limited. We have examined headspace volatile terpenes, induced by the infection of Xoo, and investigated their biological roles in the rice plant. Monoterpenes α-thujene, α-pinene, sabinene, myrcene, α-terpene, and (S)-limonene and sesquiterpenes cyclosativene, α-copaene, and β-elemene were detected from 1-week-old Xoo-infected rice seedlings, by solid-phase microextraction-gas chromatography-mass spectrometry. All monoterpenes were constitutively released from rice seedlings before Xoo infection. However, (S)-limonene emission was further elicited after exposure of the seedlings to Xoo in coincidence with upregulation of limonene synthase gene (OsTPS20) transcripts. Only the stereospecific (S)-limonene [and not (R)-limonene or other monoterpenes] severely inhibited Xoo growth, as confirmed by disc diffusion and liquid culture assays. Rice seedlings showed suppressed pathogenic symptoms suggestive of resistance to Xoo infection after foliar treatment with (S)-limonene. Collectively, our findings suggest that (S)-limonene is a volatile phytoanticipin, which plays a significant role in suppressing Xoo growth in rice seedlings.
authors.affiliation: Research Division for Biotechnology, 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.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do, 580-185, Republic of Korea.
authors.forename: Moon-Soo
authors.initials: MS
authors.lastname: Chung
authors.affiliation: Crop Foundation Research Division, National Institute of Crop Science, 181 Hyeoksin-ro, Iseo-myeon, Jeollabuk-do, 565-851, Republic of Korea.
authors.forename: Mihyung
authors.initials: M
authors.lastname: Kang
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do, 580-185, Republic of Korea. bychung@kaeri.re.kr.
authors.forename: Byung Yeoup
authors.initials: BY
authors.lastname: Chung
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do, 580-185, Republic of Korea. sungbeom@kaeri.re.kr.|Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, 113 Gwahak-ro, Yuseong-gu, Daejeon, 305-600, Republic of Korea. sungbeom@kaeri.re.kr.
authors.forename: Sungbeom
authors.initials: S
authors.lastname: Lee
mesh_terms: D053138:Cyclohexenes / Q000378:metabolism / Q000494:pharmacology*; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions / Q000502:physiology; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism; D000077222:Limonene; D039821:Monoterpenes / Q000378:metabolism / Q000494:pharmacology; D012275:Oryza / Q000378:metabolism / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism / Q000382:microbiology; D052616:Solid Phase Extraction / Q000379:methods; D013729:Terpenes / Q000378:metabolism / Q000494:pharmacology*; D014974:Xanthomonas / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity*
chemical_list: D053138:Cyclohexenes; D039821:Monoterpenes; D010940:Plant Proteins; D013729:Terpenes; D000077222:Limonene; D019753:Intramolecular Lyases; C040265:pinene cyclase I
keywords: (S)-Limonene; A disc diffusion assay; Antibacterial activity; Volatile terpene; Xanthomonas oryzae pv. oryzae