A Toolbox to Study Xenobiotic Biotransformation in Plants

PdD defence, Monday 18 June 2018, Maheswor Dev Gautam.

2018.06.18 | Trine Berndt Turtiainen Scheelke

Maheswor Dev Gautam

Maheswor Dev Gautam studied the metabolism of the fungicide azoxystrobin in plants where the substance was absorbed after spraying. The goal was to identify transformation products of azoxystrobin by mass spectrometry. A xenobiotic substance is defined as a substance that is foreign to the living organism where it has been found. Azoxystrobin is therefore a xenobiotic substance when found in a plant. Xenobiotics undergo various biotransformation reactions that constitute a mechanism of detoxification in plants. Maheswor investigated the metabolism of azoxystrobin in lettuce (Lactuca sativa) and in corn root cultures. He used quadrupole-linear ion trap and high-resolution mass spectrometry to identify the transformation products of azoxystrobin in these plants. Maheswor's results show, above all, that mass spectrometry is extremely useful for identifying xenobiotic metabolites. His research led to the identification of several known and unidentified metabolites derived from azoxystrobin in plants. In addition, Maheswor developed methods for sample preparation and simultaneous determination of azoxystrobin and its transformation products. Finally, Maheswor has developed a model system based on maize root cultures that proved to be a fast and effective method of studying the transformation of azoxystrobin in plants. The results from this PhD project provide a toolbox for future studies of the metabolism of other xenobiotic substances in plants. The main components of this toolbox include a method of sample preparation, an in vitro model, and mass spectrometric methods for the identification and quantification of azoxystrobin metabolites.

The PhD degree was completed at the Research Center Flakkebjerg, Department of Agroecology, Science and Technology, Aarhus University.

This résumé was prepared by the PhD student.

Time:
Monday 18 june 2018 at 12.00
Place: Auditorium Flakkebjerg, Forsøgsvej 1, 4200  Slagelse
Title of dissertation: Metabolism of azoxystrobin in plants – metabolite identification by quadrupole-linear ion trap mass spectrometry
Contact information: Maheswor Dev Gautam, e-mail:maheswor.gautam@agro.au.dk tel.: +4522442711
Members of the assessment committee:
Professor Damià Barceló, Catalan Institute for Water Research, Spain
Associate Professor Bjarne W. Strobel, Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
Associate Professor Bernd Wollenweber, (chair), Department of Agroecology, Science and Technology, Aarhus University, Denmark
Mainsupervisor
Associate Professor Inge S. Fomsgaard, Department of Agroecology, Aarhus University
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Science and Technology/GSST,
Ny Munkegade 120, building 1520, rooms 128-134, 8000 Aarhus C

PhD defence
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Revised 18.06.2018