Entity

Time filter

Source Type

Saint-Étienne, France

Mathur V.,Netherlands Institute of Ecology | Mathur V.,University of Delhi | Wagenaar R.,Netherlands Institute of Ecology | Caissard J.-C.,Jean Monnet University | And 6 more authors.
Plant, Cell and Environment | Year: 2013

While nectaries are commonly found in flowers, some plants also form extrafloral nectaries on stems or leaves. For the first time in the family Brassicaceae, here we report extrafloral nectaries in Brassica juncea. The extrafloral nectar (EFN) was secreted from previously amorphic sites on stems, flowering stalks and leaf axils from the onset of flowering until silique formation. Transverse sections at the point of nectar secretion revealed a pocket-like structure whose opening was surrounded by modified stomatal guard cells. The EFN droplets were viscous and up to 50% of the total weight was sugars, 97% of which was sucrose in the five varieties of B.juncea examined. Threonine, glutamine, arginine and glutamate were the most abundant amino acids. EFN droplets also contained glucosinolates, mainly gluconapin and sinigrin. Nectar secretion was increased when the plants were damaged by chewing above- and belowground herbivores and sap-sucking aphids. Parasitoids of each herbivore species were tested for their preference, of which three parasitoids preferred EFN and sucrose solutions over water. Moreover, the survival and fecundity of parasitoids were positively affected by feeding on EFN. We conclude that EFN production in B.juncea may contribute to the indirect defence of this plant species. For the first time, the presence of extrafloral nectar (EFN) in Brassicaceae is being reported. The EFN was secreted from pocket-like structures on stems, flowering stalks and leaf axils from the onset of flowering until silique formation in Brassica juncea. The EFN was mainly composed of sugars, but also traces of amino acids and glucosinolates were found. EFN secretion increased when the plant was damaged by herbivores and it enhanced the arrestment and sustenance of nectar-foraging parasitoids, indicating that EFN may act as an indirect resistance trait in B. juncea. 2012 Blackwell Publishing Ltd. Source


Caniard A.,University of British Columbia | Caniard A.,Jean Monnet University | Caniard A.,Laboratoire BVpam | Zerbe P.,University of British Columbia | And 12 more authors.
BMC Plant Biology | Year: 2012

Background: Sclareol is a diterpene natural product of high value for the fragrance industry. Its labdane carbon skeleton and its two hydroxyl groups also make it a valued starting material for semisynthesis of numerous commercial substances, including production of Ambrox® and related ambergris substitutes used in the formulation of high end perfumes. Most of the commercially-produced sclareol is derived from cultivated clary sage (Salvia sclarea) and extraction of the plant material. In clary sage, sclareol mainly accumulates in essential oil-producing trichomes that densely cover flower calices. Manool also is a minor diterpene of this species and the main diterpene of related Salvia species.Results: Based on previous general knowledge of diterpene biosynthesis in angiosperms, and based on mining of our recently published transcriptome database obtained by deep 454-sequencing of cDNA from clary sage calices, we cloned and functionally characterized two new diterpene synthase (diTPS) enzymes for the complete biosynthesis of sclareol in clary sage. A class II diTPS (SsLPPS) produced labda-13-en-8-ol diphosphate as major product from geranylgeranyl diphosphate (GGPP) with some minor quantities of its non-hydroxylated analogue, (9 S, 10 S)-copalyl diphosphate. A class I diTPS (SsSS) then transformed these intermediates into sclareol and manool, respectively. The production of sclareol was reconstructed in vitro by combining the two recombinant diTPS enzymes with the GGPP starting substrate and in vivo by co-expression of the two proteins in yeast (Saccharomyces cerevisiae). Tobacco-based transient expression assays of green fluorescent protein-fusion constructs revealed that both enzymes possess an N-terminal signal sequence that actively targets SsLPPS and SsSS to the chloroplast, a major site of GGPP and diterpene production in plants.Conclusions: SsLPPS and SsSS are two monofunctional diTPSs which, together, produce the diterpenoid specialized metabolite sclareol in a two-step process. They represent two of the first characterized hydroxylating diTPSs in angiosperms and generate the dihydroxylated labdane sclareol without requirement for additional enzymatic oxidation by activities such as cytochrome P450 monoxygenases. Yeast-based production of sclareol by co-expresssion of SsLPPS and SsSS was efficient enough to warrant the development and use of such technology for the biotechnological production of scareol and other oxygenated diterpenes. © 2012 Caniard et al.; licensee BioMed Central Ltd. Source


Nicole F.,University of Lyon | Nicole F.,Jean Monnet University | Nicole F.,Laboratoire BVpam | Guitton Y.,University of Lille Nord de France | And 10 more authors.
Bioinformatics | Year: 2012

MSeasy performs unsupervised data mining on gas chromatography-mass spectrometry data. It detects putative compounds within complex metabolic mixtures through the clustering of mass spectra. Retention times or retention indices are used after clustering, together with other validation criteria, for quality control of putative compounds. The package generates a fingerprinting or profiling matrix compatible with NIST mass spectral search program and ARISTO webtool (Automatic Reduction of Ion Spectra To Ontology) for molecule identification. Most commonly used file formats, NetCDF, mzXML and ASCII, are acceptable. A graphical and user-friendly interface, MSeasyTkGUI, is available for R novices. © The Author 2012. Published by Oxford University Press. All rights reserved. Source


Ibanez S.,CNRS Alpine Ecology Laboratory | Ibanez S.,Joseph Fourier University | Dotterl S.,University of Bayreuth | Anstett M.-C.,French National Center for Scientific Research | And 8 more authors.
New Phytologist | Year: 2010

•Floral scents and visual cues of the globeflower Trollius europaeus may play a key role in the attraction of Chiastocheta flies, involved in a highly specific nursery pollination mutualism. •Here, headspace collection and GC-MS were used to identify and quantify the volatile organic compounds emitted by the globeflower. •Scents are produced in three different floral parts by four structures: secretory glands and flat epidermis cells in the abaxial sepal epidermis, conical cells in the adaxial sepal epidermis, and pollen. The blend is made up of 16 compounds commonly found in floral scents. Geographical variation among populations is low compared with variation amongst individuals within populations. Electroantenno-graphic analyses revealed that six compounds emitted by both anthers and sepals are detected by Chiastocheta flies. Removing the anthers hidden inside the globe from flowers in the field decreased the number of fly visits to globeflowers. •A multivariate analysis of the effect of several floral traits on pollinator visitation rate conducted in the field showed that both floral scents and visual flower cues play a role in pollinator attraction. However, their relative roles and the intensity of the selective pressures exerted on floral traits by pollinators appear to vary in time and space. © The Authors (2010). Journal compilation © New Phytologist Trust (2010). Source


Guitton Y.,University of Lyon | Guitton Y.,Jean Monnet University | Guitton Y.,Laboratoire BVpam | Nicole F.,University of Lyon | And 17 more authors.
Physiologia Plantarum | Year: 2010

Despite the commercial importance of Lavandula angustifolia Mill. and L. x intermedia Emeric ex Loisel floral essential oils (EOs), no information is currently available on potential changes in individual volatile organic compound (VOC) content during inflorescence development. Calyces were found to be the main sites of VOC accumulation. The 20 most abundant VOCs could be separated into three sub-groups according to their patterns of change in concentration The three groups of VOCs sequentially dominated the global scent bouquet of inflorescences, the transition between the first and second groups occurring around the opening of the first flower of the inflorescence and the one between the second and third groups at the start of seed set. Changes in calyx VOC accumulation were linked to the developmental stage of individual flowers. Leaves accumulated a smaller number of VOCs which were a subset of those seen in preflowering inflorescences. Their nature and content remained constant during the growing season. Quantitative real time polymerase chain reaction assessments of the expression of two terpene synthase (TPS) genes, LaLIMS and LaLINS, revealed similar trends between their patterns of expression and those of their VOC products. Molecular and chemical analyses suggest that changes in TPS expression occur during lavender inflorescence development and lead to changes in EO composition. Both molecular data and terpene analysis support the findings that changes in biosynthesis of terpene occurred during inflorescence development. © 2009 Physiologia Plantarum. Source

Discover hidden collaborations