Direct suppression of a rice bacterial blight (Xanthomonas oryzae pv. oryzae) by monoterpene (S)-limonene.
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.
['Lee|Gun Woong|GW|', 'Chung|Moon-Soo|MS|', 'Kang|Mihyung|M|', 'Chung|Byung Yeoup|BY|', 'Lee|Sungbeom|S|']
D053138:Cyclohexenes D008401:Gas Chromatography-Mass Spectrometry D018506:Gene Expression Regulation, Plant D054884:Host-Pathogen Interactions D019753:Intramolecular Lyases D000077222:Limonene D039821:Monoterpenes D012275:Oryza D010935:Plant Diseases D018515:Plant Leaves D010940:Plant Proteins D036226:Seedlings D052616:Solid Phase Extraction D013729:Terpenes D014974:Xanthomonas
Xanthomonas oryzae pv. oryzae (S)-Limonene Volatile terpene A disc diffusion assay Antibacterial activity