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GC-FID coupled single-sensillum recordings (SSR) showing neuronal responses to sesquisabinene B present in Daucus carota leaf extract (a), and purified sesquisabinene B (b), in female S1 and S3 sensilla, respectively. Upper traces show SSR responses; lower
Source publication
The Carrot psyllid, Trioza apicalis Förster (Homoptera: Psylloidea: Triozidae) is one of the major insect pests of carrots (Daucus carota L.) in parts of northern and central Europe. Gas chromatography–single-sensillum recording (GC–SSR) previously confirmed several active compounds in a carrot leaf extract, but the most active compound remained un...
Contexts in source publication
Context 1
... that can be distin- guished based on differences in spike amplitudes (labelled A, B and C cells in order of decreasing amplitude). GC-SSR using carrot leaf extract confirmed previous results (Kristoffersen et al. 2008), i.e., that the peak to be identified as sesquisabinene B elicited clear responses in the C cells of sensilla S1, S2, and S3 (Fig. 3a). Subsequent GC-SSR runs using the purified product (sesquisabinene B) further con- firmed its physiological activity in sensilla S2 and S3 of both Note that different GC-columns were used in a and b sexes (Fig. 3b). However, the previously reported (Kristoffersen et al. 2008) activity also in S4 of males could not be ...
Context 2
... 2008), i.e., that the peak to be identified as sesquisabinene B elicited clear responses in the C cells of sensilla S1, S2, and S3 (Fig. 3a). Subsequent GC-SSR runs using the purified product (sesquisabinene B) further con- firmed its physiological activity in sensilla S2 and S3 of both Note that different GC-columns were used in a and b sexes (Fig. 3b). However, the previously reported (Kristoffersen et al. 2008) activity also in S4 of males could not be ...
Citations
... Secretory products of flowers are natural multi-component mixtures of volatile and non-volatile products. Terpenes, terpenoids, and molecules with an aromatic ring are present at high concentrations [4][5][6]. Volatile and semi-volatile compounds that are part of essential oils can constitute 85-99% of the entire oil fraction. Among them, there are hydrocarbon and derived mono-and sesquiterpenes, aliphatic and olefinic C 6 -C 12 The adaxial and abaxial epidermis of the ray florets was composed of elongated cells, with the central part of the surface exhibiting characteristic folding of the crested cuticle visible in the scanning electron microscope ( Figure 1C). ...
(1) Background: Centaurea cyanus L. is a medicinal plant whose flowers are widely used in herbal medicine. The aim of the study was to localise flower tissues that are responsible for the production of secretory products in petals and to analyse the volatile compounds. The volatile compounds of the flowers of this species have not been investigated to date. (2) Methods: Light, fluorescence, scanning and transmission electron microscopy techniques were used in the study. Lipophilic compounds were localised in the tissues using histochemical assays. Volatile compounds were determined with the use of solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). (3) Results: The study showed production of secretion in the petal parenchyma, whose ultrastructure has features of a secretory tissue. The lipophilic secretion was localised in the cells and intercellular spaces of the parenchyma and in the walls and surface of epidermal cells, where it accumulated after release through cuticle microchannels. Sesquiterpenes were found to constitute the main group of volatile compounds, with the highest content of β-caryophyllene (26.17%) and α-humulene (9.77%). (4) Conclusions: Given the presence of some volatile components that are often found in resins (caryophyllene, delta-cadinene) and the abundant secretion residues on the epidermal surface, we suppose that the C. cyanus secretion released by the flowers is a resinaceous mixture (oleoresin), which is frequently found in plants, as shown by literature data. This secretion may play an important role in the therapeutic effects of C. cyanus flowers.
... In contrast, the more generalistic vector, the planthopper Hyalesthes obsoletus possess a higher number of olfactory neurons and a complex primary olfactory center (antennal lobe), enabling H. obsoletus to process more complex information (Romani et al., 2009;Rossi Stacconi et al., 2014). Regardless, most investigated vector species show olfactory sensitivity towards host plant volatiles in electrophysiological (Sharon et al., 2005;Coutinho-Abreu et al., 2014;George et al., 2016;Gallinger et al., 2019;Rahmani et al., 2019;Anderbrant et al., 2020) and behavioral studies (Gross & Mekonen, 2005;Sharon et al., 2005;Mayer & Gross, 2007;Mazzoni et al., 2009). ...
Phytopathogens are responsible for devastating plant diseases threatening agriculture and food security worldwide. Phloem-restricted bacterial plant pathogens belonging to the classes mollicutes ('Candidatus Phytoplasma', Spiroplasma), α-proteobacteria, and γ-proteobacteria have a significant impact on several high-value crops. These bacteria are obligate parasites, depending on their plant and insect hosts. Inside the plants, they are restricted to the phloem, which is a source of primary and secondary plant metabolites representing a suitable niche for them. Additionally, phloem sap is utilized for nutrition by multiple Hemipterans and several species within the leafhopper, planthopper, and psyllid taxa, which can acquire and transmit the phloem-dwelling bacteria during feeding. The present review aims at providing an overview of interactions between phloem-restricted bacterial plant pathogens and their vector insects, which are mediated by primary and secondary plant metabolites. The overview is organized in two sections describing the current knowledge of phloem and volatile metabolite mediated interactions between pathogens, their host plants, their vector insects, and where information is available, the antagonists of vectors. This bibliographic oriented part is followed by a comprehensive synthesis of the reviewed literature and important research gaps were identified. The evolution of plant-pathogen-vector systems and novel trends on pest management strategies of phloem-restricted bacteria, in which semiochemicals are applied, are discussed. Finally, an outlook on future prospects is given.
... Of the plant VOCs, the most intensively studied substance group has been the terpenoids [9]. Five-carbon isoprene units, including a wide variety of monoterpenoids and sesquiterpenoids, are emitted from a wide range of species [10]. ...
Background
Plants are known to emit diverse volatile organic compounds (VOCs), which may function as signaling substances in plant communication with other organisms. Thuja occidentalis, which is widely cultivated throughout China, releases aromatic VOCs into the air in winter and early spring. The relationship of this cultivated plant with its neighboring plants is necessary for the conservation of biodiversity.
Results
(−)-α-thujone (60.34 ± 5.58%) was found to be the major component in VOCs from the Shenyang population. The essential oils (EOs) from the Kunming and Shenyang populations included the major components (−)-α-thujone, fenchone, (+)-β-thujone, and (+)-hibaene, identified using GC-MS analyses. (−)-α-thujone and (+)-hibaene were purified and identified by NMR identification. EOs and (−)-α-thujone exhibited valuable phytotoxic activities against seed germination and seedling growth of the plants Taraxacum mongolicum and Arabidopsis thaliana. Moreover, the EOs displayed potent inhibitory activity against pathogenic fungi of maize, including Fusarium graminearum, Curvularia lunata, and Bipolaris maydis, as well as one human fungal pathogen, Candida albicans. Quantitative analyses revealed high concentrations of (−)-α-thujone in the leaves of T. occidentalis individuals from both the Shenyang and Kunming populations. However, (−)-α-thujone (0.18 ± 0.17 μg/g) was only detected in the rhizosphere soil to a distance of 0.5 m from the plant.
Conclusions
Taken together, our results suggest that the phytotoxic effects and antifungal activities of the EOs and (−)-α-thujone in T. occidentalis certainly increased the adaptability of this plant to the environment. Nevertheless, low concentrations of released (−)-α-thujone indicated that reasonable distance of T. occidentalis with other plant species will impair the effects of allelochemical of T. occidentalis.
... The compounds in the carrot extract, eliciting response in the C cell of S1-S3, have unknown behavioural roles. The peripheral response pattern to the carrot extract is identical to that found for the unknown "peak 7" in the study of Kristoffersen et al. (2008), which recently was identified as sesquisabinene B (Rahmani et al., 2019). The four active synthetic compounds are all present in conifers. ...
... and S4A) responding strongly and most often exclusively to nonanal, #3 (S1B) responding moderately strongly to terpinolene, #4 (S2B and S3B) responding strongly to (Z)-3-hexenal and most often weaker to terpinolene, #5 (S1C, S2C and S3C) responding exclusively to carrot leaf extract and in particular to sesquisabinene B (Rahmani et al., 2019). Thus, testing these SSR-active compounds for behavioural responses would be of large interest for investigating the role of odours for carrot psyllid orientation and host choice. ...
Carrot psyllids (Trioza apicalis) pose a constant threat to carrot production in parts of Europe, and treatments with chemical insecticides are common. To be able to develop alternative control tactics, more knowledge about the psyllid's host‐finding behaviour and underlying physiology is needed. Using single‐sensillum recordings from overwintered and non‐overwintered males and females, we found essentially identical responses for the two groups and for both sexes. Using six compounds emanating from carrots or conifers, the psyllids' overwintering plants, and extracts of carrot leaves, five different olfactory sensory neuron classes could be distinguished from our high‐quality recordings, viz. #1 responding strongly and exclusively to terpinene‐4‐ol, #2 responding strongly and most often exclusively to nonanal, #3 responding moderately strongly to terpinolene, #4 responding strongly to (Z)‐3‐hexenal and most often weaker to terpinolene, #5 responding exclusively to carrot extract.
As universally known, gas chromatography (GC) coupled with mass spectrometry (MS) allows us to acquire spectra that can be searched in specific databases to attain qualitative information on a peak of interest. When not present in databases, structure elucidation is required before including a new component in a library: from that moment, scientists all around the world will be able to identify the new molecule with analytical confidence after GC-MS analysis. Conversely, if data are not shared in commercial databases, even if a molecule is studied and elucidated, it appears to be unknown or only identifiable on the basis of third-party data taken from the literature, which is a serious limitation. The present paper deals with a case that confirms this assumption. A component of Myrtus communis L. volatile fraction was tentatively identified based on literature data. Despite this, reliable identification could not be achieved due to the lack of a corresponding spectrum in commercial MS databases. Afterwards, the target component was isolated in a reasonable quantity and with a high degree of purity for downstream characterization by spectroscopic techniques. For this purpose, preparative (prep) GC may appear insufficient for the isolation of volatile components from highly complex samples. In this study, a prep-MDGC system was implemented for the isolation of the compound of interest from myrtle oil, consisting of three wide-bore columns of different selectivity coupled by means of Deans switch transfer devices. Based on the NMR and GC-FTIR data acquired, the unknown compound was identified as 2,2,5,5,7,7-hexamethyl-3,7-dihydro-1-benzofuran-4,6(2H,5H)-dione. Noticeably, this is a known molecule, yet its mass spectrum had never been registered into MS databases and thus was not available to the scientific community. Finally, the spectrum was included for the first time in a commercial library, namely the FFNSC 5.0 MS database. The aim of the present study was to highlight the opportunity to make analytical data quickly available in a reliable way by registering them in searchable MS databases to improve the identification means for researchers all over the world.
Chemical composition and bioactivities including bacterial and fungal resistance of the essential oils extracted from leaves of Piper betle L. (T) and Cleistocalyx operculatus L. (V) and aerial parts of Ageratum conyzoides L. (H) were investigated. The components presenting in the essential oils of the natural sources were analysized by a gas chromatography–mass spectrometry. Molecular docking simulation was utilised to support an antimicrobial mechanism of the essential oil compounds on Candida albicans fungus and Streptococcus pyogenes bacteria. This was based on the inhibition of the extracted compounds onto the microbial proteins, i.e. 4ESW and P0C0C7, respectively. There are 32 compounds identified in total in the three essential oils. The most effective inhibitors are the following: (i) chavicol acetate (T3), eugenol acetate (T11) and eugenol (T4) found in Piper betle L.; (ii) precocene II (H10) and precocene I (H6) found in Ageratum conyzoides L.; and (iii) caryophyllene oxide (V15) and cis-Lanceol (V19) found in Cleistocalyx operculatus L.. The overall antifungal and antibacterial capability of the investigated essential oils given indirect justification via their average inhabitability towards the two proteins accords with the order Piper betle L. Ageratum conyzoides L. Cleistocalyx operculatus L.. The results suggest these as promising natural sources for antimicrobial remedies.
The control of carrot psyllid Trioza apicalis Förster largely relies on chemical measures, and the current integrated pest management (IPM) strategy is based on pest scouting. The number of active ingredients available for psyllid control will further decline in the coming years. The need for alternative control measures is therefore urgent. In this work the efficiency of different control programs including a kaolin particle film and plant‐derived, crude saponin extract, chemical control, insect net and IPM (kaolin in combination with insecticides) programs to reduce psyllid feeding damage, reproduction and the spread of “Candidatus Liberibacter solanacearum” (CLso) in carrots was studied. Each year in 2016–2018, four replicates of each treatment were randomised in a row‐column design on a commercial carrot farm. After the treatments were executed, the psyllid nymphs and eggs were counted. At the harvest, the carrot roots and shoots were weighed, damages assessed, and samples were taken for CLso detection from 50 plants at each replicate. Kaolin treatment alone and in combination with insecticides effectively reduced the number of psyllid nymphs and eggs in all the years studied. Saponin was applied only on the first year, since it significantly increased the number of T. apicalis eggs compared to other treatments. The insect net was superior to other treatments in all the studied aspects in all the years. Under normal weather conditions, the highest root weight was harvested under the insect net, followed by the chemical control program consisting of pyrethroids, kaolin treatment, untreated control and saponin treatment. During extreme weather conditions, chemical control programs were not effective at protecting the carrots from psyllid feeding, which was reflected as low root yield. In all years, the carrot leaf damage percent negatively correlated with the root weight. Similarly, the shoot:root ratio increased as the leaf‐curling percentage rose, which was even pronounced under drought stress. The effect of climatic stress should be considered when developing IPM strategies.
