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Wageningen, Netherlands

van der Hooft J.J.J.,Wageningen University | van der Hooft J.J.J.,Netherlands Metabolomics Center | Vervoort J.,Wageningen University | Vervoort J.,Netherlands Metabolomics Center | And 5 more authors.
Metabolomics | Year: 2012

The identification of large series of metabolites detectable by mass spectrometry (MS) in crude extracts is a challenging task. In order to test and apply the so-called multistage mass spectrometry (MS n) spectral tree approach as tool in metabolite identification in complex sample extracts, we firstly performed liquid chromatography (LC) with online electrospray ionization (ESI)-MS n, using crude extracts from both tomato fruit and Arabidopsis leaf. Secondly, the extracts were automatically fractionated by a NanoMate LC-fraction collector/injection robot (Advion) and selected LC-fractions were subsequently analyzed using nanospray-direct infusion to generate offline in-depth MS n spectral trees at high mass resolution. Characterization and subsequent annotation of metabolites was achieved by detailed analysis of the MS n spectral trees, thereby focusing on two major plant secondary metabolite classes: phenolics and glucosinolates. Following this approach, we were able to discriminate all selected flavonoid glycosides, based on their unique MS n fragmentation patterns in either negative or positive ionization mode. As a proof of principle, we report here 127 annotated metabolites in the tomato and Arabidopsis extracts, including 21 novel metabolites. Our results indicate that online LC-MS n fragmentation in combination with databases of in-depth spectral trees generated offline can provide a fast and reliable characterization and annotation of metabolites present in complex crude extracts such as those from plants. © 2011 Springer Science+Business Media, LLC. Source

Agency: Narcis | Branch: Project | Program: Completed | Phase: Agriculture | Award Amount: | Year: 2007


Agency: Narcis | Branch: Project | Program: Completed | Phase: Agriculture | Award Amount: | Year: 2007


News Article
Site: http://phys.org/biology-news/

Plant experts in the Netherlands can still become enthusiastic about a special variety of broomrape. Farmers in southern countries, however, are less impressed because broomrape and its 'sister' striga are considered a harmful weed in these regions. Research in the Laboratory of Plant Physiology of Wageningen University shows how useful insects that can control this weed may lend a helping hand in the future, namely via the plant's own aromatic substances. "You can also use a mixture of aromatic substances to distinguish various varieties of parasitic plants," says Harro Bouwmeester, professor in plant physiology. Several varieties of broomrape and striga are parasitic plants, requiring the root system of other plants to survive. As broomrape reaches its northern distribution limit in the Netherlands it is less common and causes fewer problems for farmers. In Southern Europe, the Middle East and Africa, however, the opposite is the case. There the parasitic plants can become a very harmful weed in crops such as tomatoes, sunflowers, maize and sorghum. In Israel tomato farmers are combating the broomrape with herbicides, for instance, but the plants themselves may offer a biological alternative. Each variety of broomrape emits a complex of over 100 types of volatile aromatic substances. Some of these aromatic signals are picked up by insects that are harmful to the plant as they lay their eggs in the ovaries, after which the larvae eat the young seeds. "If we can identify those specific aromatic substances, we would be able to lure the insects to the plants with extra aromas and deploy them as a potential biological control method," Harro Bouwmeester explains. While searching for useable aromatic substances, Peter Tóth, post doc in Bouwmeester's group, discovered another practical application of the aromatic substances from broomrape: they can help identify one variety from another. In taxonomy (the science involving the description and classification of plants) there is still uncertainty about the description and classification of the various broomrape varieties: which genus do they belong to? By looking at the composition of the aromatic mix, Tóth and his colleagues were able to classify a number of these 'disputed varieties' in the proper taxonomic genus. Their findings were described in the magazine Frontiers in Plant Science this month. "In addition, we found a difference between the aromas of parasitic and non-parasitic broomrape varieties," Bouwmeester continues. "This may teach us something about how these varieties evolved into weeds. Some varieties that have yet to become harmful have an aromatic composition resembling that of the harmful varieties. We believe this means that these varieties, too, will eventually become weeds." In time Bouwmeester hopes that the research into the aromatic substances of broomrape will lead to biological control of the weed. "For farmers in Southern Europe it could mean an alternative to the herbicides they use now. For farmers in Africa, who often cannot afford herbicides at all, this could be a sustainable alternative to labour-intensive weed control. They now try to remove the weeds by hand, with large parts of the harvests being lost as a result."

Yang T.,Plant Research International | Stoopen G.,Plant Research International | Yalpani N.,DuPont Pioneer | Vervoort J.,Laboratory of Biochemistry | And 8 more authors.
Metabolic Engineering | Year: 2011

Many terpenoids are known to have antifungal properties and overexpression of these compounds in crops is a potential tool in disease control. In this study, 15 different mono- and sesquiterpenoids were tested in vitro against two major pathogenic fungi of maize (Zea mays), Colletotrichum graminicola and Fusarium graminearum. Among all tested terpenoids, geranic acid showed very strong inhibitory activity against both fungi (MIC<46 μM). To evaluate the possibility of enhancing fungal resistance in maize by overexpressing geranic acid, we generated transgenic plants with the geraniol synthase gene cloned from Lippia dulcis under the control of a ubiquitin promoter. The volatile and non-volatile metabolite profiles of leaves from transgenic and control lines were compared. The headspaces collected from intact seedlings of transgenic and control plants were not significantly different, although detached leaves of transgenic plants emitted 5-fold more geranyl acetate compared to control plants. Non-targeted LC-MS profiling and LC-MS-MS identification of extracts from maize leaves revealed that the major significantly different non-volatile compounds were 2 geranic acid derivatives, a geraniol dihexose and 4 different types of hydroxyl-geranic acid-hexoses. A geranic acid glycoside was the most abundant, and identified by NMR as geranoyl-6-O-malonyl-Β-d-glucopyranoside with an average concentration of 45 μM. Fungal bioassays with C. graminicola and F. graminearum did not reveal an effect of these changes in secondary metabolite composition on plant resistance to either fungus. The results demonstrate that metabolic engineering of geraniol into geranic acid can rely on the existing default pathway, but branching glycosylation pathways must be controlled to achieve accumulation of the aglycones. © 2011 Elsevier Inc. Source

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