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Research project (§ 26 & § 27)
Duration : 2020-09-01 - 2023-08-31

Reducing herbicide use is an important social and environmental goal, as concern is growing about the development of herbicide-resistant weeds and the ecological consequences of herbicide application. Several cover crops are known to successfully suppress weeds, providing a pertinent answer to this problem. However, in order to use cover crops adequately, the mechanisms of weed suppression need to be elucidated and understood. Besides direct resource competition, growth repression through root interactions can play a decisive role. However, so far rhizosphere interactions of two neighboring plants have received little attention in the scientific community. In previous experiments we could demonstrate that below ground interactions between the cover crops Fagopyrum esculentum (buckwheat) and Avena strigosa (black oat) led to growth suppression of Amaranthus retroflexus (redroot pigweed), presumably induced by specific cover crop root exudates. Based on these findings, we aim to further investigate cover crop root exudates and to identify putative growth suppressive compounds. We will test six research hypotheses: (H1) The selected cover crops can recognize the presence of heterospecific neighbors via interacting root systems, which leads to a systemic modification of cover crop root exudation. (H2) Certain compound groups and/or specific molecules respond to a species-specific recognition, while others respond more generally to the presence of another plant. (H3) Certain compound groups and/or specific molecules from cover crop root exudates are responsible for growth suppressive effects. (H4) Growth suppressive effects are reflected by transcriptome changes of Arabidopsis thaliana (thale cress) and Brachypodium distachyum (stiff brome). (H5) Arabidopsis thaliana and Brachypodium distachyum root exudation is altered by the presence of different cover crops. (H6) Putative compounds responsible for growth repression can be detected in agricultural soil. Our methodological approach employs a validated split-root set-up enabling differential root exudate collection and analysis. First experiments will be performed in undisturbed soil-free glass bead cultures. Differential chemical analysis of the collected exudates will follow an already implemented workflow utilizing accurate mass spectrometry in combination with fit-for-purpose separation methods. Identity confirmation of significant compounds will make use of dedicated accurate mass databases including information on fragment spectra. Subsequently, root exudates will be collected from soil grown roots and rhizosphere soil solution to confirm their presence in soil. Moreover, phenotypic and transcriptomic changes induced by direct interaction of roots and the impact of selected compounds will be studied in Arabidopsis thaliana and Brachypodium distachyum. The results of the studies will provide novel insights in belowground plant-plant interactions and provide information for the development and use of weed suppressive cover crops, as a step towards new cultural control strategies for integrated weed management.
Research project (§ 26 & § 27)
Duration : 2019-04-01 - 2021-03-31

The project entitled ‘Renewable turbulent flow chromatography for exposomics’ will be developed by Dr. David J. Cocovi-Solberg in BOKU under supervision of Dr. Stephan Hann and involves the design of novel analytical systems for automating all analysis steps in ‘exposome’ studies. Traditional studies for detection of environmental contaminants refer to the total amount of specific target substances found in different environmental compartments. Contrariwise, exposome studies try to investigate potential toxicity based on the whole pool of substances and metabolites to which human beings might be exposed to during their lifetime cycle. Those exposome studies are very complicated because up to thousands of substances present in very small amounts (down to parts per billion) are to be measured in each sample, and many samples must be analyzed to get conclusive results. Mass spectrometers are the instruments of choice for such studies. As a drawback, these analytical platforms are very sensitive to external conditions, and exposome samples cannot be analyzed directly. Samples must be pretreated with cumbersome procedures involving many steps, high amounts of chemicals and many working hours in order to remove sample constituents that could falsify the LC-MS results and negatively affect instrument performance and durability. For this reason, the project carried out at the University of BOKU aims at designing novel approaches based on pumps, valves and 3D printed components that will automatically, that is, without analyst intervention, take the sample, remove interfering sample constituents, concentrate the substances of interest that are present in very small amounts, and in general, prepare the sample for the LC-MS analysis. The heart of the instrument to be designed is based on the principle named ‘Turbulent Flow Chromatography’ (TFC), that is known for long time ago but passed unnoticed until very recently. This principle relies upon the favorable effects that happen when the sample is passed at a high speed on a bed of microscopic beads for separation of substances of interest. Thanks to advances in new materials, computer control and 3D printing technology, the TFC principle will be revisited and a proof of concept of the instrument designed. The computer-controlled operation along with the flexibility of the designed instrument will allow very complicated sequences to be executed, for analyzing different families of substances, and all in unmanned operation, that is, no scientific supervision will be needed during the entire analysis workflow.
Research project (§ 26 & § 27)
Duration : 2018-12-05 - 2021-12-04

Despite the significant advantages that combining ion mobility mass spectrometry with all-ions QTOFMS, the highly complex nature of samples faced in metabolomics studies still poses great challenges for routine use of such workflows in metabolomics. One approach to address this limitation is the use of drift-time dependent quadrupole transmission profiles to facilitate a “bandpass” selection of precursor ions to be fragmented in the collision cell. In such a workflow, the transmission and/or collision energy applied in the high energy frame can be further directed by the drift separation (i.e. the quadrupole transmission is programmed to suit the drift times of relevant metabolites). This technology has enormous potential for metabolomics, but has not been tested or assessed with relevant compounds or real samples. In this project, we propose to investigate the use of continuous wide-band quadrupole isolation in combination with ion mobility separation to establish optimized acquisition settings and comprehensive datamining workflows with an outlook toward critical applications covering both identification and relative quantification in biological and environmental samples.

Supervised Theses and Dissertations