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Protoplasma. 2015 Jul;252(4):997-1007. doi: 10.1007/s00709-014-0735-8. Epub 2014 Nov 28.

Rice terpene synthase 20 (OsTPS20) plays an important role in producing terpene volatiles in response to abiotic stresses.

Author information

1
Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do, 580-185, Republic of Korea.

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.

PMID:
25430981
DOI:
10.1007/s00709-014-0735-8
[Indexed for MEDLINE]

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