Maize root culture as a model system for studying azoxystrobin biotransformation in plants Maheswor Gautam a , Mohamed Elhiti b, 1 , Inge S. Fomsgaard a, * a Department of Agroecology, Research Center Flakkebjerg, Aarhus University, Forsøgsvej 1, 4200, Slagelse, Denmark b Department of Molecular Biology and Genetics, Research Center Flakkebjerg, Aarhus University, Forsøgsvej 1, 4200, Slagelse, Denmark highlights  Fast and easy-to-handle maize root model to study xenobiotic metabolism in plants.  Azoxystrobin metabolism in the model comparable to that in a real plant of another species.  Mass spectrometric confirmation of azoxystrobin metabolites. article info Article history: Handling Editor: T. Cutright Keywords: Hairy root Xenobiotic Metabolism Plant Model Root Phytoremediation abstract Hairy roots induced by Agrobacterium rhizogenes are well established models to study the metabolism of xenobiotics in plants for phytoremediation purposes. However, the model requires special skills and resources for growing and is a time-consuming process. The roots induction process alters the genetic construct of a plant and is known to express genes that are normally absent from the non-transgenic plants. In this study, we propose and establish a non-transgenic maize root model to study xenobiotic metabolism in plants for phytoremediation purpose using azoxystrobin as a xenobiotic compound. Maize roots were grown aseptically in Murashige and Skoog medium for two weeks and were incubated in 100 mM azoxystrobin solution. Azoxystrobin was taken up by the roots to the highest concentration within 15 min of treatment and its phase I metabolites were also detected at the same time. Conjugated metabolites of azoxystrobin were detected and their identities were confirmed by enzymatic and mass spectrometric methods. Further, azoxystrobin metabolites identified in maize root culture were compared against azoxystrobin metabolites in azoxystrobin sprayed lettuce grown in green house. A very close similarity between metabolites identified in maize root culture and lettuce plant was obtained. The results from this study establish that non-transgenic maize roots can be used for xenobiotic metabolism studies instead of genetically transformed hairy roots due to the ease of growing and handling. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Plants have defensive mechanism by which foreign chemicals, called xenobiotics, are metabolized through a cascade of enzymatic reactions broadly categorized as Phase I and phase II metabolism (Sandermann,1994; Huber et al., 2012; Chen et al., 2016). Ideally, a xenobiotic compound is metabolized to its more hydrophilic form through phase I and phase II metabolism and finally sequestered in vacuoles or cell walls. Phase I reactions are initiated by cytochrome P450 complex leading to oxidation, reduction or hydroxylation of xenobiotics. Typically, a phase II reaction in plants involves conju- gation of phase I metabolites with glucose, glutathione or malonyl- glucose. Glucosylation is catalyzed by glucosyl-transferase enzyme. Further, a glucoside conjugate can subsequently get converted to malonyl glucoside conjugate due to the action of malonyl-CoA transferase (Sandermann Jr., 1992). The information on xenobiotic metabolites in plants is required during new pesticide active ingredient development (Mullins, 1993) or for human and envi- ronmental safety assessment (E.F.S.A, 2012). The metabolic fate of xenobiotics in plants have been studied using model systems (Van Eerd et al., 2003; Myung et al., 2013) due to the associated advantages of rapid growth and control of photo * Corresponding author. E-mail address: inge.fomsgaard@agro.au.dk (I.S. Fomsgaard). 1 Current address: Department of Plant Sciences, University of Manitoba, Man- itoba, Canada. Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2017.12.121 0045-6535/© 2017 Elsevier Ltd. All rights reserved. Chemosphere 195 (2018) 624e631