Identification of key gene networks controlling monoterpene biosynthesis during grape ripening by integrating transcriptome and metabolite profiling

Monoterpenes are typical aroma components of muscat grape cultivars,providing pleasant floral and fruity aromas to grapes and wines.However,the molecular mechanism of monoterpene biosynthesis between muscat and non-muscat grape remains unclear.Here,the muscat grape cultivar‘Jumeigui’and the non-muscat grape cultivar‘Kyoho’were chosen as plant materials for a comprehensive transcriptome and metabolite analysis.The gas chromatography-mass spectrometry(GC-MS)analysis demonstrated that a total of 27 and 23 monoterpene compounds were identified and quantified in the‘Jumeigui’and‘Kyoho’grape,respectively.‘Jumeigui’grape accumulated significantly higher concentrations of monoterpenes than‘Kyoho’grape.Furthermore,geraniol,linalool,geranic acid,and β-citronellol might be important odorants contributing to the floral character of the‘Jumeigui’grape due to the high levels odor activity values(OAVs).Transcriptome analysis demonstrated that the expression profiles of VvDXS,VvGGPPS.SSU1,Vv TPS-b/g showed a positive correlation with monoterpene accumulation in grapes.In addition,the expression patterns of the genes involved in jasmonic acid(JA)synthesis and signal were also positively correlated with monoterpene accumulation.All these results will help guide the functional verification of candidate genes related to monoterpene biosynthesis,as well as identify the master transcriptional and hormonal regulators of this pathway in grapes.

Structural characterization of monoterpene indole alkaloids in ethanolic extracts of Rauwolfia species by liquid chromatography with quadrupole time-of-flight mass spectrometry

Rauwolfia species(Apocynaceae) are medicinal plants well known worldwide due to its potent bioactive monoterpene indole alkaloids(MIAs) such as reserpine,ajmalicine,ajmaline,serpentine and yohimbine.Reserpine,ajmalicine and ajmaline are powerful antihypertensive,tranquilizing agents used in hypertension.Yohimbine is an aphrodisiac used in dietary supplements.As there is no report on the comparative and comprehensive phytochemical investigation of the roots of Rauwolfia species,we have developed an efficient and reliable liquid chromatography-tandem mass spectrometry(LC–MS/MS) method for ethanolic root extract of Rauwolfia species to elucidate the fragmentation pathways for dereplication of bioactive MIAs using highperformance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry(HPLC–ESI–QTOF–MS/MS) in positive ion mode.We identified and established diagnostic fragment ions and fragmentation pathways using reserpine,ajmalicine,ajmaline,serpentine and yohimbine.The MS/MS spectra of reserpine,ajmalicine,and ajmaline showed C-ring-cleavage whereas E-ring cleavage was observed in serpentine via Retro Diels Alder(RDA).A total of 47 bioactive MIAs were identified and characterized on the basis of their molecular formula,exact mass measurements and MS/MS analysis.Reserpine,ajmalicine,ajmaline,serpentine and yohimbine were unambiguously identified by comparison with their authentic standards and other 42 MIAs were tentatively identified and characterized from the roots of Rauwolfia hookeri,Rauwolfia micrantha,Rauwolfia serpentina,Rauwolfia verticillata,Rauwolfia tetraphylla and Rauwolfia vomitoria.Application of LC–MS followed by principal component analysis(PCA) has been successfully used to discriminate among six Rauwolfia species.

Monoterpene Glycosides from the Roots of Paeonia lactiflora

A new monoterpene glycoside, together with nine known ones, 3-O-methylpaeoniflorin, mudanpioside J, paeoniflorin, benzoylpaeoniflorin, oxypaeoniflorin, benzoyloxypaeoniflorin, oxybenzoylpaeoniflorin, albiflorin and lactiflorin, was isolated from the roots of Paeonia lactiflora Pall.. The structure of the new compound was elucidated as galloylalbiflorin by the spectro- scopic evidence including ESI-MS, 1D- and 2D-NMR spectra.

Paeonivayin, A New Monoterpene Glycoside from Paeonia delavayi

A new monoterpene glycoside named paeonivayin with other seven known compounds were isolated from the roots of Paeonia delavayi Franch. and their structures were determined by means of spectroscopic studies.

Two New Monoterpene Diglycosides from Winchia calophylla A.DC

Two new monoterpene diglycosides, wincaloside A (1) and wincaloside B (2), along with loganin (3) were isolated from the stem barks of Winchia calophylla A. DC. The structures of 1 and 2 were established by spectroscopic and chemical methods.

A New Monoterpene Glycoside from Swertia punicea

A new monoterpene glycoside, 2,6-dimethyl-2E,6E-octadienoic acid 1,6'-lactone 8-beta-D-glucopyranoside, was isolated from Swertia punicea, accompanying with six known compounds 1-O-primeverosyl-3,7-dimethoxy-8-hydroxyxanthone, 1-O-primeverosyl-3,7,8-tri-methoxyxan-thone, epi-eustomoside, 1-hydroxy-3,7,8-trimethoxyxanthone, 1,8-dihydroxy-3,7-dimethoxy xanthone and isovitexine. Their structures were elucidated based on spectral evidence.

A New Monoterpene Glycoside from Paeonia veitchii

A new monoterpene glycoside, acetoxypaeoniflorin, was isolated from the root cortex of Paeonia veitchii Lynch.. The structure was elucidated by spectral methods.

A New Monoterpene Glucoside from the Leaves of Betula platyphylla Suk.

A new monoterpene glucoside. (2E,67.)-2.6-dimethyl-8-beta -D-glucosyloxy-2,6-octadienoic acid, was isolated from the leaves of Betula platyphylla Suk. The structure was established by spectroscopic data.

A Novel Monoterpene Glycoside from Swertia mileensis

A novel monoterpene glycoside, mileenside, was isolated from Swertia mileensis by repeated normal and reverse phase silica gel chromatography and its structure was elucidated mainly based on spectral evidence.

New monoterpene phenyl ethers from Illicium micranthum

Seven new monoterpene phenyl ethers,namely micranthumnins A-G(1-7),were isolated from the stem bark of Illicium micranthum(Illiciaceae).Their structures were elucidated by comprehensive spectroscopic analyses including MS,IR,1D and 2D NMR.All compounds were evaluated for their anti-AChE activities.

Two new monoterpene glycosides from Doellingeria scaber

Two new methane-type monoterpene glycosides were isolated from the roots of Doellingeria scaber. Their structures were identified as trans-p-menthane-1α,2β,8-triol 8-O-β-D-（3′,6′-diangeloyloxy）-glucopyranoside and trans-p-menthane-1α,2β,8-triol 8-O-β-D-（3′-angeloyloxy,6′-isobutyloxy）-glucopyranoside based on 1D and 2D NMR spectroscopy.

Larvicidal efficacy of monoterpenes against the larvae of Anopheles gambiae

Objective:To evaluate the larvicidal efficacy of eight volatile components of essential oils against 3rd instar larvae of Anopheles gambiae s.s.Methods:Larvicidal effects of each compound were evaluated in both laboratory and semi-field trials.Stock solution was prepared and serial dilutions were made in six concentrations for each compound.A total of 20 larvae were exposed to larvicides for each replicate and monitored at intervals of 12,24,48 and 72 h.Larvae monitoring was done on basis of dead and live larvae in all intervals.Results:All assayed compounds were larvicides and presented varying degrees of larval toxicity,with LC50 values ranging from 1.28 to 1 938.92 mg/L depending on the treatment time(12,24,48 or 72 h).(-)-Perillyl alcohol presented the strongest larvicidal activity towards Anopheles gambiae larvae,with LC_(50) values of 73.60,18.36,1.72 and1.28 mg/L after 12,24,48 and 72 h of exposure,respectively.The next strongest were(-)-isopulegol(LC_(50)= 135.10,49.39,34.39 and 20.22 mg/L) and(-)-carvone epoxide(LC_(50)= 168.86,124.74,80.84 and 23.46 mg/L).After 12,24 and 48 h of treatment,hydroxydihydrocarvone was the least toxic compound,with LC_(50) values of 1 938.92,1 172.18 and 401.03 mg/L,respectively.Conclusions:The data obtained in this study suggest that all evaluated monoterpenes,especially(-)-perillyl alcohol,have remarkable larvicidal effects and may be considered as potential sources for the development of suitable natural larvicides for mosquito management programs.Further small-scale field trials should be conducted.

Highly Oxygenated Monoterpenes from Eupatorium fortunei

A pair of epimers of highly-oxygenated monoterpenes were isolated from the traditional Chinese medicine Eupatorium fortunei. Their structures were elucidated on the basis of the spectral analysis as （1R＊, 2S＊, 3R＊, 4R＊, 6S＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （1） and （1S＊, 2S＊, 3S＊, 4R＊, 6R＊）-1, 2, 3, 6-tetrehydroxy-p-menthane （2）.

Monoterpene hydrocarbons,major components of the dried leaves essential oils of five species of the genus Eucalyptus from Cote d’Ivoire

The chemical composition of the essential oils obtained from the dried leaves of five species of the genus Eucalyptus (E. camaldulensis, E. de-glupta, E. grandis, E. torelliana, E. urophylla) growing in C?te d’Ivoire, was analyzed by means of GC and GC/MS. The density and the refractive index were measured. The major components of all these oils are: α-pinene, β-pinene, α-phellandrene, limonene, γ-terpinene, p-cymene and β-caryo-phyllene. The particularity of these oils is their monoterpene hydrocarbons major components.

Heteromeric and Homomeric Geranyl Diphosphate Synthases from Catharanthus roseus and Their Role in Monoterpene Indole Alkaloid Biosynthesis

Catharanthus roseus is the sole source of two most important monoterpene indole alkaloid （MIA） anti- cancer agents： vinblastine and vincristine. MIAs possess a terpene and an indole moiety derived from terpenoid and shikimate pathways, respectively. Geranyl diphosphate （GPP）, the entry point to the formation of terpene moiety, is a product of the condensation of isopentenyl diphosphate （IPP） and dimethylallyl diphosphate （DMAPP） by GPP synthase （GPPS）. Here, we report three genes encoding proteins with sequence similarity to large subunit （CrGPPS.LSU） and small subunit （CrGPPS.SSU） of heteromeric GPPSs, and a homomeric GPPSs. CrGPPS.LSU is a bifunctional enzyme producing both GPP and geranyl geranyl diphosphate （GGPP）, CrGPPS.SSU is inactive, whereas CrGPPS is a homomeric enzyme forming GPP. Co-expression of both subunits in Escherichia coil resulted in heteromeric enzyme with enhanced activity producing only GPR While CrGPPS.LSU and CrGPPS showed higher expression in older and younger leaves, respectively, CrGPPS.SSU showed an increasing trend and decreased gradually. Methyl jasmonate （MelA） treatment of leaves sig- nificantly induced the expression of only CrGPPS.SSU. GFP localization indicated that CrGPPS.SSU is plastidial whereas CrGPPS is mitochondrial. Transient overexpression of AmGPPS.SSU in C. roseus leaves resulted in increased vindoline, immediate monomeric precursor of vinblastine and vincristine. Although C. roseus has both heteromeric and homomeric GPPS enzymes, our results implicate the involvement of only heteromeric GPPS with CrGPPS.SSU regulating the GPP flux for MIA biosynthesis.

Product Variability of the ‘Cineole Cassette＇ Monoterpene Synthases of Related Nicotiana Species

Nicotiana species of the section Alatae characteristically emit the floral scent compounds of the ＇cineole cassette＇ comprising 1,8-cineole, limonene, myrcene, α-pinene, β-pinene, sabinene, and α-terpineol. We successfully isolated genes of Nicotiana alata and Nicotiana langsdorfii that encoded enzymes, which produced the characteristic monoter- penes of this ＇cineole cassette＇ with α-terpineol being most abundant in the volatile spectra. The amino acid sequences of both terpineol synthases were 99% identical. The enzymes cluster in a monophyletic branch together with the closely related cineole synthase of Nicotiana suaveolens and monoterpene synthase 1 of Solanum lycopersicum. The cyclization reactions （α-terpineol to 1,8-cineole） of the terpineol synthases of N. alata and N. langsdorfii were less efficient compared to the ＇cineole cassette＇ monoterpene synthases of Arabidopsis thaliana, N. suaveolens, Salvia fruticosa, Salvia officinalis, and Citrus unshiu. The terpineol synthases of IV. alata and N. langsdorfii were localized in pistils and in the adaxial and abaxial epidermis of the petals. The enzyme activities reached their maxima at the second day after anthesis when flowers were fully opened and the enzyme activity in N. alata was highest at the transition from day to night （diurnal rhythm）.

Atmospheric isoprene and monoterpenes in a typical urban area of Beijing： Pollution characterization, chemical reactivity and source identification

Continuous observation of isoprene, β-pinene and β-pinene was carried out in a typical urban area of Beijing from March 2014 to February 2015, using an AirmoVOC online analyzer. Based on the analysis of the ambient level and variation characteristics of isoprene, β-pinene and β- pinene, the chemical reactivity was studied, and their sources were identified. Results showed that the concentrations of isoprene, α-pinene and β-pinene in the urban area of Beijing were lower than those in richly vegetated areas; the concentrations of isoprene were at a moderate level compared with those of previous studies of Beijing. Concentrations of isoprene, α-pinene and β-pinene showed different seasonal, monthly, daily and diurnal variations, and all of the three species showed higher level at night than those in the daytime as a whole, the variations of isoprene, α-pinene and β-pinene mainly influenced by emission of sources, photochemical reaction, and meteorological parameters. Isoprene was the largest contributor to the total OFP values than β-pinene and β-pinene. α-Pinene was the largest contributor to the total SOAFP values than isoprene and β-pinene in autumn, while isoprene was the largest one in other seasons. Isoprene, α-pinene and β-pinene were derived mainly from biological sources; and α- pinene level were also affected by industrial sources. To reduce the concentrations of isoprene, α-pinene and β-pinene, it is necessary to scientifically select urban green plant species, and more strict control measures should be taken to reduce the emission of β-pinene from industrial sources, such as artificial flavors and resins synthesis processes.

Characteristics and possible origins of atmospheric monoterpenes from nonliving plants in Guangzhou

Monoterpenes in ambient air were determined in various sites in Guangzhou, and it was revealed that monoterpene concentrations in some special sites, like landfills, were even higher than those in locations with much more vegetation. On the average, monoterpene contents in samples from streets and highways were 1.9 μg/m3; from gardens, plantations and wooded lands, 2.2 μg/m3; from farmlands, 1.5 μg/m3; but from landfills, 4.1 μg/m3. So other sources like landfills, apart from living plants, might also contribute to the biogenic non-methane hydrocarbons (NMHCs) in the atmospheric environment. On the other hand, the composition pattern of monoterpenes in air samples from landfills were obviously different compared with those from living plants, this might result from the different synthesis pathways of monoterpenes, the oxygen-depleted environment and the microbiogenic process might affect the synthesis in landfills.

Spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes

Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long-range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short-range host plant choice by both adult females and larvae of a folivorous forest pest （Choristoneura fumiferana）. We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix （α-pinene, β-pinene, limonene, myrcene） and to white spruce （Picea glauca） epicuticular waxes in closed arenas. Ovipositing females pre- ferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes ＋ monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene-treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax-only discs, but showed no preference between extremely high monoterpene concentrations and wax-only controls. In an insect-free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg-laying females and feeding larvae, and that their effects are synergistic.